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Alcohol calculations are carried out in many forensic case types. On occasion, individuals under the age of 18 are involved, and alcohol calculations may be beneficial. To date, there are no studies that have determined the best way to estimate total body water (TBW) or alcohol elimination rates in juveniles for alcohol calculations. We utilized a data set of 207 females and 218 males, aged 3-18 years, from a variety of ethnic backgrounds, where TBW had been empirically measured, to evaluate the best anthropometric equation to use to estimate TBW in juveniles. For males aged 3-15 years and females aged 2-13 years, the equation of Wells et al. was the most accurate and precise (RMSE of ≤10.4% in males and ≤9.9% in females). For males aged 16+ years and females aged 14+ years, the equation of Watson et al. was more appropriate (RMSE ≤11.5% and ≤12.4%, respectively). Based on published studies where the alcohol elimination rate was determined in 43 juveniles (aged 10-17 years) who were hospitalized due to alcohol consumption, a mean alcohol elimination rate of 16 mg/100 mL/h should be used. The recommended range being 9-25 mg/100 mL (5th-95th percentile). This study provides evidence that there are valid anthropometric equations to determine TBW and alcohol elimination rates that can be used for alcohol calculations in juveniles between the ages of 10 and 17., (© 2024 American Academy of Forensic Sciences.)

Background: Plasma volume (PV) calculated from hematocrit and body weight has applications in cardiovascular disease. The current study investigated the validity of the calculated PV for predicting volume overload and its prognostic utility in patients undergoing hemodialysis (HD)., Patients and Methods: Fifty-four HD patients were prospectively enrolled, and their actual PV (aPV) and relative PV status (PVS) were calculated. Bioelectrical impedance analysis (BIA) with assessment of and total body water (TBW), intracellular water (ICW), extracellular water (ECW), and overhydration (OH) and routine blood examinations were performed before dialysis. A second cohort of 164 HD patients was retrospectively enrolled to evaluate the relationship between the calculated PVS and the outcome, with an endpoint of all-cause mortality., Results: aPV was significantly associated with TBW, ICW, ECW, OH, and ECW/TBW (all p  < 0.001), and most strongly with ECW ( r  = 0.83). aPV predicted the extent of volume overload with an AUC of 0.770 ( p  < 0.001), but PVS did not (AUC = 0.617, p  = 0.091). Median follow-up time was 53 months, during the course of which 60 (36.58%) patients died. Values for PVS (12.94 ± 10.87% vs. 7.45 ± 5.90%, p  = 0.024) and time-averaged PVS (12.83 ± 11.20 vs. 6.78 ± 6.22%, p  < 0.001) were significantly increased in patients who died relative to those who survived. A value of time-averaged PVS >8.72% was significantly associated with an increased incidence of all-cause mortality (HR = 2.48, p  = 0.0023)., Conclusions: aPV was most strongly associated with ECW measured using BIA. HD patients with higher time-averaged PVS had a higher rate of all-cause mortality.

Bioelectrical impedance analysis (BIA) is a method used to estimate body composition, and it relies mainly on the body's water content. Insufficient body water can introduce bias to body composition scores., Purpose: To determine the effect of body weight loss elicited by passive dehydration on body composition scores, including phase angle (PhA)., Methods: Twenty-five euhydrated apparently healthy and physically active men's (age = 22.6 ± 3.3 yr.; body mass = 76.7 ± 15.9 kg; height = 172.0 ± 6.3 cm) body composition variables and PhA were measured before and after sitting quietly for 5 h in a controlled environment (26.6 ± 1.7 °C, 72 ± 4.9%RH)., Results: It was found that five hours of passive dehydration caused a loss in body weight (Δ = 0.76 ± 0.34 kg, p < 0.05) and a decrease in body fat estimation (Δ = 0.90 ± 0.87 kg, p < 0.001). Additionally, an increase in ECW (Δ = 0.12 ± 0.30 L, p < 0.021) and PhA (Δ = 0.10 ± 0.15°, p < 0.005) was observed., Conclusion: Body weight loss due to passive dehydration decreased BIA-derived fat mass, and increased extracellular water and PhA in physically active and apparently healthy men. Nonetheless, these changes had a negligible effect on the accuracy of the equipment, rendering them clinically insignificant.

Background: Skin hydration (SKH) measurements are used for multiple purposes: to study skin physiology, to clinically investigate dermatological issues, and to assess localized skin water in pathologies like diabetes and lymphedema. Often the volar forearm is measured at various times of day (TOD). This report aims to characterize intra-day variations in volar forearm SKH to provide guidance on expected TOD dependence., Materials and Methods: Forty medical students (20 male) self-measured tissue dielectric constant (TDC) on their non-dominant forearm in triplicate as an index of local skin tissue water every 2 h starting at 0800 and ending at 2400 h. All were trained and pre-certified in the procedure and had whole-body fat (FAT%) and water (H 2 O%) measured. Day average TDC (TDC AVG ) was determined as the average of all time points expressed as mean ± SD., Results: Males versus females had similar ages (25.1 ± 2.2 years vs. 25.1 ± 1.5 years), higher H 2 O% (56.6 ± 5.0 vs. 51.8 ± 5.7, p = 0.002), and higher TDC AVG (32.7 ± 4.1 vs. 28.5 ± 5.1, p = 0.008). TDC values were not significantly impacted by H 2 O% or FAT%. Female TDC exhibited a significant decreasing trend from morning to night (p = 0.004); male TDC showed no trend., Conclusion: Skin water assessed by TDC shows some intra-day variations for females and males but with quite different temporal patterns. Clinical relevance relates to the confidence level associated with skin hydration estimates when measured at different times of day during normal clinic hours which, based on the present data, is expected to be around 5% for both males and females., (© 2024 The Author(s). Skin Research and Technology published by John Wiley & Sons Ltd.)

Objective: Cross-sectional evidence has demonstrated that parallel reactance obtained by bioelectrical impedance analysis (BIA) may be an alternative to the regularly used series of measurements to predict intracellular water (ICW) in athletes. However, we are not aware of any studies that have determined the predictive role or compared the effectiveness of both series and parallel reactance for tracking ICW changes during an athletic season. The main aim of this study was to determine the predictive role and compare both series and parallel reactance (Xc) in tracking ICW during an athletic season., Research Methods and Procedures: This longitudinal study analyzed 108 athletes in the preparatory and competitive periods. Using dilution techniques, total body water (TBW) and extracellular water (ECW) were determined and ICW was calculated. Resistance (R), Xc, and impedance (Z) standardized for height were obtained through BIA spectroscopy using a frequency of 50kHz in a series array and then mathematically transformed in a parallel array., Results: Multiple regression analyses showed that only changes in parallel Xc and capacitance (CAP) (P < 0.05) were predictors of delta ICW during the sports season. In contracts, this was not the case for Xcs. Both changes in R and Z, series and parallel, predicted similarly the changes in ECW and TBW (P < 0.05) in athletes., Conclusion: Our findings highlight the potential of parallel BIA values to detect changes in body water compartments over a competitive season. These data provide preliminary evidence that changes in parallel Xc/H, and ultimately CAP, represent valid markers of alterations in cell volume during a sports season., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The application of stable isotope analysis (SIA) to the fields of ecology and animal biology has rapidly expanded over the past three decades, particularly with regards to water analysis. SIA now provides the opportunity to monitor migration patterns, examine food webs, and assess habitat changes in current and past study systems. While carbon and nitrogen SIA of biological samples have become common, analyses of oxygen or hydrogen are used more sparingly despite their promising utility for tracing water sources and animal metabolism. Common ecological applications of oxygen or hydrogen SIA require injecting enriched isotope tracers. As such, methods for processing and analyzing biological samples are tailored for enriched tracer techniques, which require lower precision than other techniques given the large signal-to-noise ratio of the data. However, instrumentation advancements are creating new opportunities to expand the applications of high-throughput oxygen and hydrogen SIA. To support these applications, we update methods to distill and measure water derived from biological samples with consistent precision equal to, or better than, ± 0.1 ‰ for δ 17 O, ± 0.3 ‰ for δ 18 O, ± 1 ‰ for δ 2 H, ± 2 ‰ for d -excess, and ± 15 per meg for Δ 17 O.

Background: Water is one of the most essential nutrients for life. The water turnover (WT), total body water (TBW), and total energy expenditure (TEE) can be measured using the doubly labeled water (DLW) method. WT and TBW are lower in older adults than in young adults, and the former are susceptible to dehydration, necessitating to identify predictors of the WT in older adults., Objectives: The current study aimed to examine the association between WT and physical activity, physical function, and body composition in Japanese adults aged ≥65 y and identify predictors for WT in this population., Methods: This study enrolled 133 older adults (women, n = 61; men, n = 72) aged 65-88 y. WT, TBW, TEE, fat-free mass (FFM), and percent body fat (%Fat) were determined using the DLW method. The fitness age score (FAS) was obtained from 5 physical fitness tests. Physical activity and the step count were assessed using a previously validated triaxial accelerometer. Multiple regression analyses were performed with WT as the dependent variable., Results: WT was positively associated with weight, physical activity level (PAL), moderate-vigorous physical activity, and TEE, and negatively associated with sedentary behavior. We examined potential predictors for WT using age, sex, height, weight, FFM, %Fat, TEE, PAL, and FAS in older Japanese adults., Conclusions: Our results confirmed that age, sex, weight, FFM, TEE, and PAL are the potential predictors of WT in older Japanese adults aged ≥65 y., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

We aim to understand the effects of hydration changes on athletes' neuromuscular performance, on body water compartments, fat-free mass hydration and hydration biomarkers and to test the effects of the intervention on the response of acute dehydration in the hydration indexes. The H2OAthletes study (clinicaltrials.gov ID: NCT05380089) is a randomised controlled trial in thirty-eight national/international athletes of both sexes with low total water intake (WI) (i.e. < 35·0 ml/kg/d). In the intervention, participants will be randomly assigned to the control (CG, n 19) or experimental group (EG, n 19). During the 4-day intervention, WI will be maintained in the CG and increased in the EG (i.e. > 45·0 ml/kg/d). Exercise-induced dehydration protocols with thermal stress will be performed before and after the intervention. Neuromuscular performance (knee extension/flexion with electromyography and handgrip), hydration indexes (serum, urine and saliva osmolality), body water compartments and water flux (dilution techniques, body composition (four-compartment model) and biochemical parameters (vasopressin and Na) will be evaluated. This trial will provide novel evidence about the effects of hydration changes on neuromuscular function and hydration status in athletes with low WI, providing useful information for athletes and sports-related professionals aiming to improve athletic performance.

Purpose: To identify the risk factors for training-related lower extremity muscle injuries in young males by a non-invasive method of body composition analysis., Methods: A total of 282 healthy young male volunteers aged 18 - 20 years participated in this cohort study. Injury location, degree, and injury rate were adjusted by a questionnaire based on the overuse injury assessment methods used in epidemiological studies of sports injuries. The occurrence of training injuries is monitored and diagnosed by physicians and treated accordingly. The body composition was measured using the BodyStat QuadScan 4000 multifrequency Bio-impedance system at 5, 50, 100 and 200 kHz to obtain 4 impedance values. The Shapiro-Wilk test was used to check whether the data conformed to a normal distribution. Data of normal distribution were shown as mean ± SD and analyzed by t-test, while those of non-normal distribution were shown as median (Q 1 , Q 3 ) and analyzed by Wilcoxon rank sum test. The receiver operator characteristic curve and logistic regression analysis were performed to investigate risk factors for developing training-related lower extremity injuries and accuracy., Results: Among the 282 subjects, 78 (27.7%) developed training injuries. Lower extremity training injuries revealed the highest incidence, accounting for 23.4% (66 cases). These patients showed higher percentages of lean body mass (p = 0.001), total body water (TBW, p = 0.006), extracellular water (p = 0.020) and intracellular water (p = 0.010) as well as a larger ratio of basal metabolic rate/total weight (p = 0.006), compared with those without lower extremity muscle injuries. On the contrary, the percentage of body fat (p = 0.001) and body fat mass index (p = 0.002) were lower. Logistic regression analysis showed that TBW percentage > 65.35% (p = 0.050, odds ratio = 3.114) and 3rd space water > 0.95% (p = 0.045, odds ratio = 2.342) were independent risk factors for lower extremity muscle injuries., Conclusion: TBW percentage and 3rd space water measured with bio-impedance method are potential risk factors for predicting the incidence of lower extremity muscle injuries in young males following training., (Copyright © 2024 Chinese Medical Association. Production and hosting by Elsevier B.V. All rights reserved.)

Background: The morbidity and mortality of chronic kidney disease (CKD) are increasing worldwide, making it a serious public health problem. Although a potential correlation between body water content and CKD progression has been suggested, the presence of a causal association remains uncertain. This study aimed to determine the causal effect of body water content on kidney function., Methods: Genome-wide association study summary data sourced from UK Biobank were used to evaluate single-nucleotide polymorphisms (SNPs) associated with whole-body water mass (BWM). The summary statistics pertaining to kidney function were extracted from the CKDGen consortium. The primary kidney function outcome measures included estimated glomerular filtration rate (eGFR), albuminuria, CKD stages 3-5, and rapid progression to CKD (CKDi25). Two-sample Mendelian randomization (MR) analysis estimated a potential causal relationship between the BWM and kidney function. The inverse variance weighted MR method was used as the primary analysis, accompanied by several sensitive MR analyses., Results: The increase of BWM exhibited a correlation with a reduction in eGFR (β = -0.02; P = 6.95 × 10 -16 ). Excluding 13 SNPs responsible for pleiotropy ( P = 0.05), the increase of BWM was also associated with the decrease of the ratio of urinary albumin to creatinine (β = -0.16; P = 5.91 × 10 -36 ). For each standard deviation increase in BWM, the risk of CKD stages 3-5 increases by 32% (OR, 1.32; 95% CI, 1.19-1.47; P = 1.43 × 10 -7 ), and the risk of CKDi25 increases by 22% (OR, 1.22; 95% CI, 1.07-1.38; P = 0.002)., Conclusion: The increase of BWM is associated with impaired kidney function. Proactively managing body water content is of great significance in preventing the progression of CKD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wei, Long, Fan, Hou, Yang, Qu and Du.)

Human skin acts as a protective barrier, preserving bodily functions and regulating water loss. Disruption to the skin barrier can lead to skin conditions and diseases, emphasizing the need for skin hydration monitoring. The gold-standard sensing method for assessing skin hydration is the Corneometer, monitoring the skin's electrical properties. It relies on measuring capacitance and has the advantage of precisely detecting a wide range of hydration levels within the skin's superficial layer. However, measurement errors due to its front end requiring contact with the skin, combined with the bipolar configuration of the electrodes used and discrepancies due to variations in various interfering analytes, often result in significant inaccuracy and a need to perform measurements under controlled conditions. To overcome these issues, we explore the merits of a different approach to sensing electrical properties, namely, a tetrapolar bioimpedance sensing approach, with the merits of a novel optical sensing modality. Tetrapolar bioimpedance allows for the elimination of bipolar measurement errors, and optical spectroscopy allows for the identification of skin water absorption peaks at wavelengths of 970 nm and 1450 nm. Employing both electrical and optical sensing modalities through a multimodal approach enhances skin hydration measurement sensitivity and validity. This layered approach may be particularly beneficial for minimising errors, providing a more robust and comprehensive tool for skin hydration assessment. An ex vivo desorption experiment was carried out on fresh porcine skin, and an in vivo indicative case study was conducted utilising the developed optical and bioimpedance sensing devices. Expected outcomes were expressed from both techniques, with an increase in the output of the optical sensor voltage and a decrease in bioimpedance as skin hydration decreased. MLR models were employed, and the results presented strong correlations (R-squared = 0.996 and p -value = 6.45 × 10 -21 ), with an enhanced outcome for hydration parameters when both modalities were combined as opposed to independently, highlighting the advantage of the multimodal sensing approach for skin hydration assessment.

Background: Athletes vary in hydration status due to ongoing training regimes, diet demands, and extreme exertion. With water being one of the largest body composition compartments, its variation can cause misinterpretation of body composition assessments meant to monitor strength and training progress. In this study, we asked what accessible body composition approach could best quantify body composition in athletes with a variety of hydration levels., Methods: The Da Kine Study recruited collegiate and intramural athletes to undergo a variety of body composition assessments including air-displacement plethysmography (ADP), deuterium-oxide dilution (D 2 O), dual-energy X-ray absorptiometry (DXA), underwater-weighing (UWW), 3D-optical (3DO) imaging, and bioelectrical impedance (BIA). Each of these methods generated 2- or 3-compartment body composition estimates of fat mass (FM) and fat-free mass (FFM) and was compared to equivalent measures of the criterion 6-compartment model (6CM) that accounts for variance in hydration. Body composition by each method was used to predict abdominal and thigh strength, assessed by isokinetic/isometric dynamometry., Results: In total, 70 (35 female) athletes with a mean age of 21.8 ± 4.2 years were recruited. Percent hydration (Body Water 6CM /FFM 6CM ) had substantial variation in both males (63-73 %) and females (58-78 %). ADP and DXA FM and FF M had moderate to substantial agreement with the 6C model (Lin's Concordance Coefficient [CCC] = 0.90-0.95) whereas the other measures had lesser agreement (CCC <0.90) with one exception of 3DO FFM in females (CCC = 0.91). All measures of FFM produced excellent precision with %CV < 1.0 %. However, FM measures in general had worse precision (% CV < 2.0 %). Increasing quartiles (significant p < 0.001 trend) of 6CM FFM resulted in increasing strength measures in males and females. Moreover, the stronger the agreement between the alternative methods to the 6CM, the more robust their correlation with strength, irrespective of hydration status., Conclusion: The criterion 6CM showed the best association to strength regardless of the hydration status of the athletes for both males and females. Simpler methods showed high precision for both FM and FFM and those with the strongest agreement to the 6CM had the highest strength associations., Summary Box: This study compared various body composition analysis methods in 70 athletes with varying states of hydration to the criterion 6-compartment model and assessed their relationship to muscle strength. The results showed that accurate and precise estimates of body composition can be determined in athletes, and a more accurate body composition measurement produces better strength estimates. The best laboratory-based techniques were air displacement plethysmography and dual-energy x-ray absorptiometry, while the commercial methods had moderate-poor agreement. Prioritizing accurate body composition assessment ensures better strength estimates in athletes., Competing Interests: Conflict of interest JS received an investigator-initiated grant from Hologic, Inc. to fund the larger study and other grants on body composition from Hologic and GE Healthcare. SH is on the Medical Advisory Board for Tanita Corporation. TK is a current employee at Hologic. The remaining authors report no conflicts of interest., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Although water is essential to the maintenance of health and life, standard values for human water requirements are yet to be determined. This study aimed to evaluate the distribution of water turnover (WT) according to sex and age, estimated using a prediction equation, in Japanese adolescents and adults., Methods: This cross-sectional study used data from the 2016 National Health and Nutrition Survey, Japan. Data were obtained from electronically available aggregated reports in the survey's official website. Participants aged between 15 and 80 years (10,546 men, 12,355 women) were selected using stratified random sampling. WT was calculated considering lifestyle and environmental factors, and using an equation (coefficient of determination = 0.471) previously developed by the international doubly labelled water (DLW) database group. As data on physical activity levels (PAL) were not collected in the survey, we used two evaluation methods: (1) energy intake assessed by dietary records and (2) total energy expenditure measured by the DLW method reported in previous Japanese studies, divided by basal metabolic rate predicted using the equation. We evaluated the relationship between WT and age using a restricted cubic spline model., Results: The average WT for the 15-19, 20-29, 30-39, 40-49, 50-59, 60-69, and ≥ 70 years was 3291, 3151, 3213, 3243, 3205, 3104, and 2790 ml/day, respectively in men, and 2641, 2594, 2741, 2739, 2753, 2707, and 2482 ml/day, respectively in women. In the spline model, WT showed an inverse association with age in men older than 50 years, whereas women showed a reverse U-shaped relationship between WT and age (p for non-linearity < 0.001), although results differed with body weight adjustment. Similar results were found for both PAL evaluation methods, and the range of WT per body weight was 45-56 ml/day for both sexes., Conclusions: We determined the standard values of WT in Japanese population using a prediction equation and national large-scale survey data. These findings may be useful for setting water requirements for dietary guidelines in future., (© 2023. The Author(s).)

Background: The aim of this study was to determine the predictive role of series and parallel bioelectrical impedance-derived parameters in predicting total body (TBW), intracellular (ICW), and extracellular water (ECW) in athletes., Methods: This cross-sectional study analyzed 134 male (21.33 ± 5.11 years) and 64 female (20.45 ± 5.46 years) athletes. Using dilution techniques, TBW and ECW were determined while ICW was the difference between both. Raw and standardized for height (/H) bioelectrical resistance (R), reactance (Xc), and impedance (Z) values were obtained using a phase-sensitive device at a single frequency in a series array (s). These were mathematically transformed in a parallel array (p) and capacitance (CAP). Fat-free mass (FFM) was assessed by dual-energy X-ray absorptiometry., Results: Multiple regressions adjusted for age and FFM show that R/Hs, Z/Hs, R/Hp, and Z/Hp were significant predictors of TBW (p < 0.001 in females and males). While Xc/Hs did not predict ICW, Xc/Hp was a predictor (p < 0.001 in females and Males). In females, R/H and Z/H predicted similarly TBW, ICW, and ECW. In males, R/Hs was considered a better predictor than R/Hp for TBW and ICW, and the Xc/Hp was considered the best predictor for ICW. Another significant predictor of ICW was CAP (p < 0.001 in females and males)., Conclusion: This study highlights the potential value of parallel bioelectrical impedance values to identify fluid compartments in athletes as an alternative to the regularly used series measurements. Moreover, this study supports Xc in parallel, and ultimately CAP, as valid indicators of cell volume., (© 2023 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Background: Bioelectrical impedance analysis (BIA) is a minimally invasive, safe, easy, and quick technology used to determine body composition., Objectives: We compared the relationship among impedance indices obtained using single-frequency BIA, multi-frequency BIA, bioelectrical impedance spectroscopy (BIS), and skeletal muscle mass (SMM) of physically active young men and athletes using the creatine (methyl-d 3 ) dilution method. We also compared the SMM and intracellular water (ICW) of athletes and active young men measured using a reference stable isotope dilution and BIS method, respectively., Methods: We analyzed data from 28 men (mean age, 20 ± 2 y) who exercised regularly. Single-frequency BIA at 5 kHz and 50 kHz (R 5 and R 50 ), multi-frequency BIA (R 250-5 ), and BIS (R ICW ) methods of determining the SMM were compared. The deuterium and sodium bromide dilution methods of obtaining the total body water, ICW, and extracellular water measurements were also used, and the results were compared to those acquired using bioimpedance methods., Results: The correlation coefficients between SMM and L 2 /R 5 , L 2 /R 50 , L 2 /R 250-5 , and L 2 /R ICW were 0.738, 0.762, 0.790, and 0.790, respectively (P < 0.01). The correlation coefficients between ICW and L 2 /R 5 , L 2 /R 50 , L 2 /R 250-5 , and L 2 /R ICW were 0.660, 0.687, 0.758, and 0.730, respectively (P < 0.001). However, the correlation coefficients of L 2 /R 50 , L 2 /R 250-5 , and L 2 /R ICW for SMM and ICW were not significantly different., Conclusions: Our findings suggest that single-frequency BIA at L 2 /R 50 , multi-frequency BIA, and BIS are valid for assessing the SMM of athletes and active young men. Additionally, we confirmed that the SMM and ICW were correlated with single-frequency BIA, multi-frequency BIA, and BIS. Bioimpedance technologies may be dependable and practical means for assessing SMM and hydration compartment status of active young adult males; however, cross-validation is needed., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Bioimpedance analysis-assessed extracellular water/total body water (ECW/TBW) ratio may be a marker for mortality and poor nutritional status in hemodialysis patients. In 193 maintenance hemodialysis patients, we retrospectively investigated the relationships among ECW/TBW ratio, mortality, and protein-energy wasting (PEW). Four components-body mass index, normalized protein catabolic rate, normalized serum creatinine level, and serum albumin level-constitute the simple PEW score; this score was calculated based on the positive number of items concerning malnutrition among these four components. A score ≥ 3 indicated PEW. Patients were stratified by an ECW/TBW ratio cut-off value (0.40) and by PEW versus non-PEW status. The simple PEW score, cardiothoracic ratio, and log-transformed C-reactive protein level were independently correlated with the ECW/TBW ratio. Eighty-four patients died during follow-up (median 4.3 years). After adjustments for sex, age, hemodialysis vintage, histories of cardiovascular events and diabetes, and C-reactive protein level, a higher ECW/TBW ratio and PEW were independently related to elevated risks of all-cause death. Adding the ECW/TBW ratio to a baseline risk model including PEW significantly increased C-statistics from 0.788 to 0.835. In conclusion, the ECW/TBW ratio may be an indicator of PEW and may be a predictor of death even accounting for PEW, in hemodialysis patients., (© 2023. Springer Nature Limited.)

Physiological differences have been reported between individuals who have habitual low (LOW) and high (HIGH) water intake (WI). The aims of this study were to explore body water compartments, hydration status, and fat-free mass (FFM) hydration of elite athletes exposed to different habitual WI. A total of 68 athletes (20.6 ± 5.3 years, 23 females) participated in this observational cross-sectional study. Total WI was assessed by seven-day food diaries and through WI, athletes were categorized as HIGH (n = 28, WI≥40.0 mL/kg/d) and LOW (n = 40, WI≤35.0 mL/kg/d). Total body water (TBW) and extracellular water (ECW) were determined by dilution techniques and intracellular water (ICW) as TBW-ECW. Hydration status was assessed by urine-specific gravity (USG) using a refractometer. Fat (FM) and FFM were assessed by dual-energy X-ray absorptiometry (DXA). The FFM hydration was calculated by TBW/FFM. The USG was statistically different between groups for females (LOW: 1.024 ± 0.003; HIGH: 1.015 ± 0.006; p = 0.005) and males (LOW: 1.024 ± 0.002; HIGH: 1.018 ± 0.005; p < 0.001). No differences between groups were detected in body water compartments and FFM hydration in both sexes (p > 0.05). Multiple regression showed that WI remains a predictor of USG regardless of FFM, age, and sex (β = -0.0004, p < 0.01). We concluded that LOW athletes were classified as dehydrated through USG although their water compartments were not different from HIGH athletes. These results suggest that LOW athletes may expectedly maintain the body water compartments' homeostasis through endocrine mechanisms. Interventions should be taken to encourage athletes to have sufficient WI to maintain optimal hydration., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Adequate hydration is essential for the maintenance of health and physiological functions in humans. However, many older adults do not maintain adequate hydration, which is under-recognized and poorly managed. Older adults are more vulnerable to dehydration, especially those living with multiple chronic diseases. Dehydration is associated with adverse health outcomes in older adults, and acts as an independent factor of the hospital length of stay, readmission, intensive care, in-hospital mortality, and poor prognosis. Dehydration is a prevalent health problem in older adults, accounting for substantial economic and social burden. This review attempts to provide current knowledge of hydration including patterns of body water turnover, the complex mechanisms behind water homeostasis, the effects of dehydration on the health of the body, and practical guidance for low-intake dehydration in older adults.

Introduction: Bioimpedance methods are currently used abundantly in patients on chronic hemodialysis. In this population, their most important role is to determine the level of fluid volume, respectively its intra- and extracellular components. There are several bioimpedance devices on the market. In this project, we compared two frequently used devices: Body Composition Monitor and InBody S10., Materials and Methods: We invited patients on chronic hemodialysis who are being treated in our institution. Inclusion criteria were: clinically stable condition, lack of artificial joints, pacemakers, or other implanted metal objects. The examinations were performed just prior to hemodialysis by both methods 5 minutes apart. Patients were examined in the supine position after 15 minutes at rest to stabilize body fluids. Studied parameters were those that are obtainable by both methods: total body water (TBW) (L), extracellular water (ECW) (L) and intracellular water (ICW) (kg), lean tissue mass (LTM) (L), and fat tissue mass (kg)., Results: We included 14 participants (aged 64.4 ± 18.0 years). Statistically and clinically significant differences between data from compared devices were observed for all variables. Inbody S10 overestimated TBW by 2.58 ± 2.73 L and ICW by 4.56 ± 2.27 L in comparison to BCM. The highest difference (27%) was measured for LTM and ICW 22%. LTM, fat, and ECW were higher when measured by BCM (LTM by 8.54 ± 6.43 kg, p < 0.001; fat by 3.41 ± 4.22, p = 0.01; ECW by 2.01 ± 0.89 L, p < 0.001)., Conclusion: The differences between tested devices were significant not only statistically, but also clinically. These two devices cannot be used interchangeably for dry weight setting of hemodialysis patients.

Background: The appendicular extracellular-to-intracellular water ratio (Ap ECW/ICW) has recently gained attention as a non-invasive measurable marker of muscle quality. However, there is a lack of basic evidence regarding age-related changes, sex differences, contribution to muscle strength independent of skeletal muscle mass (SMM), and potential improvement through physical activity (PA) in Ap ECW/ICW., Methods: This cross-sectional study enrolled 8,018 middle-aged and older Japanese individuals (aged 45-75 years). The Ap ECW/ICW and SMM were measured using segmental bioelectrical impedance spectroscopy. Muscle strength was evaluated by measuring the handgrip strength (HGS) with a dynamometer, and the PA level (PAL) was measured with an accelerometer. We performed a linear regression analysis of the associations of the Ap ECW/ICW with age, HGS, and PAL., Results: The Ap ECW/ICW increased by 0.019 for men and 0.014 for women per 5-year increase in age (p < 0.001), and the age-related increase was greater in men than in women (p for interaction <0.001). The Ap ECW/ICW was more strongly associated with the HGS than with the SMM in both men and women (p < 0.001). PAL showed a significant inverse association with the Ap ECW/ICW in both men and women (p < 0.001)., Conclusions: Ap ECW/ICW is higher with age, and it varies by sex. The Ap ECW/ICW may reflect muscle strength more than the SMM, suggesting that the Ap ECW/ICW may be improved by PA. The findings from this study may provide a framework for further Ap ECW/ICW research., Competing Interests: Declaration of Competing Interest None declared., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: This study aimed to investigate the relationship between tongue factors (tongue strength and tongue volume), systemic factors (grip strength and walking speed), and the extracellular water/total body water ratio., Methods: This cross-sectional study included community-dwelling adults. Body water composition and skeletal muscle mass index were measured using bioelectrical impedance analysis. Moreover, tongue grip strength, tongue volume, occlusal support condition (Eichner classification), and walking speed were measured. Multiple linear regression analysis was performed to investigate the relationship between the tongue and systemic factors as dependent variables and body water composition., Results: We included 171 community-dwelling adults (62 men and 109 women) aged 70.0 years (interquartile range: 8). Tongue strength (r=-0.22, P=0.004) and grip strength (r=-0.39, P<0.001) were correlated with the extracellular water/total body water ratio. In multiple linear regression analysis, tongue strength was associated with the extracellular water/total body water ratio (β=-0.20, P=0.034), and grip strength was associated with the extracellular water/total body water ratio (β=-0.12, P=0.047), sex, body mass index, skeletal muscle mass index, and occlusal support condition., Conclusions: A higher extracellular water/total body water ratio indicates lower tongue and grip strength. Dentists and dental hygienists should be aware of systemic factors present in patients with lower tongue and grip strength. These findings may lead to further medical investigations and diagnosis of other systemic diseases.

Background: Body composition can be measured by several methods, each with specific benefits and disadvantages. Bioelectric impedance offers a favorable balance between accuracy, cost and ease of measurement in a range of settings. In this method, bioelectric measurements are converted to body composition measurements by prediction equations specific to age, population and bioimpedance device. Few prediction equations exist for populations in low-resource settings. We formed a prediction equation for total body water in Malawian adolescents using deuterium dilution as reference., Methods: We studied 86 boys and 92 girls participating in the 11-14-year follow-up of the Lungwena Antenatal Intervention Study, a randomized trial of presumptive infection treatment among pregnant women. We measured body composition by Seca m515 bioimpedance analyser. Participants ingested a weight-standardized dose of deuterium oxide, after which we collected saliva at baseline, at 3 and 4 h post-ingestion, measured deuterium concentration using Fourier-transform infrared spectroscopy and calculated total body water. We formed predictive equations for total body water using anthropometrics plus resistance and reactance at a range of frequencies, applying multiple regression and repeated cross-validation in model building and in prediction error estimation., Results: The best predictive model for percentage total body water (TBW %) was 100*(1.11373 + 0.0037049*height (cm)2/resistance(Ω) at 50 kHz- 0.25778*height(m)- 0.01812*BMI(kg/m2)- 0.02614*female sex). Calculation of absolute TBW (kg) by multiplying TBW (%) with body weight had better predictive power than a model directly constructed to predict absolute total body water (kg). This model explained 96.4% of variance in TBW (kg) and had a mean prediction error of 0.691 kg. Mean bias was 0.01 kg (95% limits of agreement -1.34, 1.36) for boys and -0.01 kg (1.41, 1.38) for girls., Conclusions: Our equation provides an accurate, cost-effective and participant-friendly body composition prediction method among adolescents in clinic-based field studies in rural Africa, where electricity is available., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Näsänen-Gilmore et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objectives: Children 10-20 years old in the US are currently obese, showing suboptimal hydration as 60% fail to meet the US Dietary Reference Intakes for water. Studies have shown a significant inverse association between hydration status and body composition in children, although most failed to use the Dual-X-Ray Absorptiometry Scan (DEXA), the gold standard for body composition. Limited studies used an objective marker to measure hydration, such as urine specific gravity (USG) from a 24-h urine collection. Therefore, this study aimed to examine the association between hydration status (measured from USG in a 24-h urine sample and assessed from three 24-h dietary recalls) and body fat % and lean mass (assessed from a DEXA scan) in children (10-13 years, n=34) and adolescents (18-20 years, n=34)., Methods: Body composition was measured using DEXA, total water intake (mL/d) was assessed from three 24-h dietary recalls and analyzed using the Nutrition Data System for Research (NDSR). Hydration status was objectively measured using USG via 24-h urine collection., Results: Overall body fat % was 31.7 ± 7.31, total water intake was 1746 ± 762.0 mL/d, and USG score was 1.020 ± 0.011 uG. Linear regressions showed significance between total water intake and lean mass (B=12.2, p<0.05). Logistic regressions showed no significant association between body composition and USG and total water intake., Conclusions: Findings showed total water intake was significantly associated with lean mass. Future research should be conducted to explore other objective markers of hydration and with a larger sample., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Background: There is a need to detect and prevent fluid overload and malnutrition in heart failure. Bioelectrical impedance analysis and bioelectrical impedance vector analysis are medical instruments that can advance heart failure management by generating values of body composition and body water, assisting clinicians to detect fluid and nutritional status. However, there is a lack of evidence to summarise how they have been used among heart failure patients., Method: A systematic search was conducted., Result: Two hundred and four papers were screened. Forty-eight papers were reviewed, and 46 papers were included in this review. The literature shows that bioelectrical impedance analysis and bioelectrical impedance vector analysis were mostly used to assess fluid and nutritional status, together with diagnostic and prognostic values. Contraindication of using BIA and implications for practice are also demonstrated., Conclusion: The findings suggest that bioelectrical impedance vector analysis is superior to bioelectrical impedance analysis when assessing hydration/nutritional status in heart failure. Assessing a patient using bioelectrical impedance analysis /bioelectrical impedance vector analysis, together with natriuretic peptide -heart failure biomarkers, increases the diagnostic accuracy of heart failure. Further studies are required to examine the cost effectiveness of using these instruments in clinical practice.

Background & Aims: Total body water (TBW) is the largest component of fat free mass and therefore is commonly used in multi-compartment body composition models and as a stand-alone method to assess body composition. Previous literature has not validated bioelectrical impedance spectroscopy device estimates of TBW in racial and ethnic minority populations; previous studies have focused on bioelectrical impedance analysis devices that rely on proprietary algorithms and participant characteristics for accuracy. The purpose of this study was to assess the validity of two bioelectrical impedance spectroscopy devices for measures of TBW compared to a deuterium dilution criterion in a multi-ethnic sample., Methods: 109 individuals (55% female, Age: 26.6 ± 6.9 yrs, BMI: 25.3 ± 4.0 kg/m 2 ) identifying as Asian, African American/Black, Caucasian/White, Hispanic, and Multi-racial were enrolled. After a 12 h fast, participants provided a saliva sample for the criterion baseline TBW measure and completed two bioelectrical impedance device (BIS, IB) measurements of TBW. Participants then ingested deuterium oxide (D 2 O). After an equilibration period, participants provided a second saliva sample for analysis of TBW., Results: For the total multi-ethnic sample, BIS estimates demonstrated good to fairly good agreement (Total error [TE] = 2.56 L, R 2  = 0.951) and IB estimates were excellent to very good (TE = 1.95 L, R 2  = 0.975). Validity results did not vary meaningfully between race and ethnicity., Conclusions: The results suggest the BIS and IB devices evaluated can produce valid TBW estimates compared to D 2 O in a multi-ethnic sample. TBW estimates from the IB may have better agreement with D 2 O compared to the BIS when using the default settings., Competing Interests: Declaration of competing interest The authors declare there are no conflicts of interest., (Copyright © 2023 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.)

Objective: To develop and validate equations that estimate total body water (TBW) and fat-free mass (FFM) in adults using anthropometric measurements., Methods: A cross-sectional study was conducted among 178 adults (77 men and 101 women; aged 18-59 years). Participants were distributed by sex and age groups, and then randomly assigned to equal two groups; the development (n = 89) and the validation (n = 89). The anthropometric measurements included height and weight. The deuterium dilution technique (DDT) estimated TBW and FFM. Linear regression models were used with the TBW and FFM as the dependent variable, and height and weight as the independent variables. Cross-validation was performed by Bland and Altman plot, and the new anthropometric equations were developed., Results: In the validation sample, the developed equations had high R 2 of 94.4 for both TBW and FFM in all age groups, and low standard errors (RMSE: 1.80 kg for TBW and 2.44 kg for FFM). The pure error was 2.03 for the TBW equation and 2.71 for the FFM equation. The Bland-Altman plot illustrated the good level of concordance between the TBW and FFM predicted by the new equations as determined by DDT. The following developed equations showed a better agreement with the DDT: [Formula: see text]; [Formula: see text]., Conclusion: In this study, we developed and validated prediction equations for the estimation of TBW and FFM from DDT in healthy adult Tunisian population. The newly anthropometric prediction equations seem to be the most accurate for Tunisian adult., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

The bioelectrical impedance analysis-measured ratio of extracellular water (ECW) to intracellular water (ICW) reflects fluid volume and malnutrition. It may be an indicator of protein-energy wasting and muscle wasting in hemodialysis patients. We examined the association between the ECW/ICW ratio and simplified creatinine index, which is a new surrogate marker of protein-energy wasting and muscle wasting, and whether their combination can accurately predict mortality. A total of 224 patients undergoing hemodialysis for more than 6 months and having undergone bioelectrical impedance analysis for the assessment of body composition were included. Patients were divided into two groups based on the cut-off values of the ECW/ICW ratio (0.57) and simplified creatinine index (20.4 mg/kg/day) for maximumly predicting mortality. Thereafter, they were cross-classified into four groups with each cut-off point. The ECW/ICW ratio was independently associated with the simplified creatinine index (β = -0.164; P = 0.042). During a follow-up of 3.5 years (2.0-6.0 years), 77 patients died. A higher ECW/ICW ratio (adjusted hazard ratio, 3.66, 95% confidence interval 1.99-6.72, P <0.0001) and lower simplified creatinine index (adjusted hazard ratio, 2.25, 95% confidence interval 1.34-3.79, P = 0.0021) were independently associated with an increased risk of all-cause mortality. The adjusted hazard ratio for the higher ECW/ICW ratio and lower simplified creatinine index group vs. the lower ECW/ICW ratio and higher simplified creatinine index group was 12.22 (95% confidence interval 3.68-40.57, p <0.0001). Furthermore, the addition of the ECW/ICW ratio and simplified creatinine index to the baseline risk model significantly improved the C-index from 0.831 to 0.864 (p = 0.045). In conclusion, the ECW/ICW ratio may be a surrogate marker of muscle wasting. Moreover, combining the ECW/ICW ratio and simplified creatinine index may improve the accuracy of predicting all-cause mortality and help stratify the mortality risk of hemodialysis patients., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Yajima, Yajima. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Direct anthropometric measurements to assess body composition have limited precision and/or specificity., Objectives: The study aimed to develop a prediction equation based on anthropometric measurements for estimating total body water (TBW) in a healthy population., Methods: TBW was assessed using the deuterium dilution method in 398 Moroccan participants (235 women and 163 men) aged 11.6-88 y, then compared to the estimations made by previously published anthropometric equations. By sex, participants were randomly assigned into development (n = 199) and validation subgroups (n = 199). A new anthropometric equation was developed in the development subgroup from data obtained on body volume (BV), weight, and sex, where the BV was calculated from participants' height. Then the equation was validated in the validation subgroup using the Bland and Altman procedure, bias, and pure error. External validation was performed using a sample from Tunisia (n = 220, 51.8% female, 18-65 y)., Results: Bias in predicting TBW showed unacceptable value for all previously published equations as it was significantly overestimated. The following new equation using anthropometric measurements [TBW (kg) = -5.249 + 107.502 BV (L) + 0.289 weight (kg) + 2.015 sex (male: 1, female: 0); (R 2 = 0.91, RMSE = 1.885 kg)] was developed, and its internal validation was confirmed. The generated bias and pure error values were 0.047 kg (95% CI: -0.235, 0.330) and 2.02 kg (95% CI: 1.73, 2.31), respectively. The external validation of the new TBW prediction equation on a Tunisian sample showed a bias and pure error values of 0.07 kg (95% CI: -0.289, 0.429) and 2.36 kg, respectively., Conclusions: The results indicate that the new anthropometric-based prediction equation provides a good estimation of TBW and other body composition compartments. It could be recommended as an alternative method to assess body composition for epidemiological and clinical studies., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Background: Various methods, including bioelectrical impedance analysis (BIA), are used for total body water (TBW) estimation. The objective of our study by BIA was to develop a new predication model based on corrected TBW for normal adult BMI, a concept similar to the standardization of glomerular filtration rate by relating it to the average adult body surface area., Method: We measured TBW by BIA in 335 children 3-21 years old with normal or excessive body weight. Based on our data, we derived a new prediction model for TBW (L) for females {[(72.784 + 0.4093 × weight)∗Corrected TBW]/100} and males {[(57.944 + 0.6551 × weight)∗Corrected TBW]/100}. For validation, we compared our prediction model with three other models on TBW by BIA and dilution methods., Results: Our model's error size to predict TBW showed lower cross-validated root mean square error (CV-RMSE) as compared to three other models versus our dataset by BIA and two other datasets by dilution methods. Our model also showed a smaller error (2.059) in CV-RMSE as compared to other models by dilution methods (2.126, 2.873, and 4.384) for normal and excessive weight combined. This implies that our model is more robust when excessive weight individuals are included in the data.., Conclusion: Our prediction model for TBW estimation by BIA performs better as compared to some other models based on BIA and dilution method datasets. Furthermore, our prediction model is the only one that is devised to be applicable to children and young adults with both normal as well as excessive weight., Competing Interests: Conflict of interest None., (Copyright © 2022 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.)

Given that the prevalence of smartwatches has allowed them to become a hallmark in health monitoring, they are primed to provide accessible body composition estimations. The purpose of this study was to evaluate the precision and agreement of smartwatch-based bioimpedance analysis (SW-BIA) and multifrequency bioimpedance analysis (MFBIA) against a 4-compartment (4C) model criterion. A total of 186 participants (114 females) underwent body composition assessments necessary for a 4C model and SW-BIA and MFBIA. Values of total body water (TBW) from each device were compared with those obtained from bioimpedance spectroscopy. Precision was adequate though slightly lower for the smartwatch compared with other methods. No device demonstrated equivalence with the 4C model. Specifically, the SW-BIA overestimated and MFBIA underestimated body fat. MFBIA, but not SW-BIA, demonstrated equivalence for TBW. Overall error was higher for males using the smartwatch compared with females. While these findings do not invalidate the use of smartwatch-based estimates, clinicians should consider that there may be large errors relative to clinical measures. If this wearable device is intended to be used to monitor body composition change over time, these findings demonstrate the need for future research to evaluate its accuracy during follow-up testing.

Objectives: The aim of this study was to compare the data of conductance and capacitance measurements of facial skin hydration and to evaluate and discuss the advantages and disadvantages of the different approaches., Methods: We measured skin capacitance (Corneometer® CM 825) and skin conductance (Skicon-200EX®) on 30 pre-defined facial sites of 125 Chinese women, resulting in 3750 readings per device. The data were analysed and compared, and continuous colour maps were generated on a 3D avatar for capacitance, conductance, relative difference (Δ%) and correlation (R-value) by interpolating between the individual readings and converting the values to colours. This visualization allows a better interpretation of the results., Results: The complexity of facial skin hydration is revealed by this approach. The similarities and discrepancies in the facial hydration maps are clearly apparent. Due to the superiority of the Skicon in measuring high hydration levels, differences in skin hydration were evident on the forehead compared with the Corneometer maps, which may be related to the more superficial measurement of the Skicon within the stratum corneum. Conversely, a greater understanding of the complexity of facial skin hydration in the nasolabial fold was obvious when using the Corneometer. The best congruence between the instruments was found at two specific but separated facial areas, one around the inner eye region and the other one on a line between the nasolabial sulcus and the oblique, lateral jaw. Interestingly, the data were not normally distributed for both instruments and they had opposite skews. All facial clusters were statistically different from each other (p < 0.001), except the cheek and jaw for the Skicon. Larger than expected percentage coefficients of variance were found for the Corneometer on some facial sites that might be explainable by differences in stratum corneum physiology and biochemistry. Corneometer values of 48 AU and Skicon values of 132 μS were taken as the cutoff for normally hydrated facial skin., Conclusions: Both devices have their advantages and disadvantages suggesting that bio-instrumental measurement of skin hydration is actually more complicated than commonly thought and that the different facial zones and the use of multiple instrumentation have not been adequately considered., (© 2022 DSM Nutritional Products AG. International Journal of Cosmetic Science published by John Wiley & Sons Ltd on behalf of Society of Cosmetic Scientists and Societe Francaise de Cosmetologie.)

Objective: The aim of this study was to evaluate the association of differential body water composition with survival in patients with lung cancer., Methods: This retrospective cohort study included 1314 patients diagnosed with lung cancer in 80 Chinese institutions from May 2013 to August 2020. We calculated hazard ratios (HRs) to evaluate the associations of all-cause mortality with extracellular water (ECW) and intracellular water (ICW). Cox proportional risk regression models were adjusted for sociodemographic characteristics, tumor characteristics, treatment, body mass index (BMI), and body composition measures. We also evaluated cross-classification of the dichotomy of ECW and ICW with outcomes. The association among ECW, ICW, and survival was evaluated via Cox regression and the restricted cubic-spline model using a two-sided P value., Results: The study included 819 (62%) men and 495 (28%) women. The HR of lung cancer mortality significantly decreased as ECW increased (HR, 0.96; 95% confidence interval [CI], 0.93-1.00) and ICW (HR, 0.97; 95% CI, 0.95-1.00) with cutoff values of 10.5 and 16.3 L, respectively. When patients were cross-classified into categories of sex, age, BMI, visceral fat index, pathology, tumor stage, tumor burden, total bilirubin, and neutrophil count, ICW and ECW were protective factors. Only sex interacted significantly with ICW or ECW. High ICW and ECW had significant protective effects, and women had a greater risk for death than men in the case of either poor ICW or poor ECW. Sensitivity analysis showed the protective effect of the higher dichotomy of ICW (HR, 0.52; 95% CI, 0.35-0.78) and ECW (HR, 0.45; 95% CI, 0.31-0.66) on female lung cancer patients by removing patients who died within 12 mo of diagnosis., Conclusion: Greater ICW and ECW, especially ICW, were independent predictors for better survival in patients with lung cancer. Female patients were more vulnerable to dehydration than male patients., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Stratum corneum (SC) hydration is one of the most important skin biophysical parameters, which is affected by age, sex and anatomic site. We conducted a systematic review and meta-analysis to provide detailed information on baseline values of SC hydration in healthy human adults, according to the skin area, age and sex. The databases Medline, Embase, Web of Science and Scopus were searched for primary reports, with in vivo corneometry measurements, which were conducted on disease-free skin of human subjects, aged 18+ years in English. Risk of bias was evaluated using the critical appraisal tools for JBI Systematic Reviews, and only low-risk studies were selected. The comparison was performed in each skin area between males and females and also between young- and middle-age subjects. Among 323 Retrieved titles, full texts of 259 articles were read, and 240 studies were excluded due to unclear or insufficient reporting of SC hydration, as well as high or medium risk of bias. 19 studies (including 113 records) providing data about SC hydration in 12 skin areas were included in the final data synthesis. Pooled sample sizes ranged from n = 32 for lips to a maximum of n = 3202 for cheeks. The lowest hydration of 12.5 [95% CI 11.05-13.94] was reported for the back, and the highest hydration of 64.34) [95 CI% 62.07-64.59] for the periorbital area. Facial skin showed higher water content compared with other areas. There were also site-dependent differences in the hydration level of the facial skin. Comparisons between two age groups, and male and female participants, did not show any statistically significant differences. The main limitation was we included studies using only one measurement device. The quality of reporting SC hydration in humans should be increased in future studies., (© 2022 European Academy of Dermatology and Venereology.)

Introduction: Segmental eight-point bioimpedance has been increasingly used in practice. However, whether changes in bioimpedance analysis components before and after hemodialysis (HD) using this technique in a standing position is comparable to traditional whole-body wrist-to-ankle method is still unclear. We aimed to investigate the differences between two eight-point devices (InBody 770 and Seca mBCA 514) and one wrist-to-ankle (Hydra 4200) in HD patients and healthy subjects in a standing position., Methods: Thirteen HD patients were studied pre- and post-HD, and 12 healthy subjects once. Four measurements were performed in the following order: InBody; Seca; Hydra; and InBody again. Electrical equivalent models by each bioimpedance method and the fluid volume estimates by each device were also compared., Findings: Overall, total body water (TBW) was not different between the three devices, but InBody showed lower extracellular water (ECW) and higher intracellular water (ICW) compared to the other two devices. When intradialytic weight loss was used as a surrogate for changes in ECW (∆ECW) and changes in TBW (∆TBW), ∆ECW was underestimated by Hydra (-0.79 ± 0.89 L, p < 0.01), InBody (-1.44 ± 0.65 L, p < 0.0001), and Seca (-0.32 ± 1.34, n.s.). ∆TBW was underestimated by Hydra (-1.14 ± 2.81 L, n.s.) and InBody (-0.52 ± 0.85 L, p < 0.05) but overestimated by Seca (+0.93 ± 3.55 L, n.s.)., Discussion: Although segmental eight-point bioimpedance techniques provided comparable TBW measurements not affected by standing over a period of 10-15 min, the ECW/TBW ratio appeared to be significantly lower in InBody compared with Seca and Hydra. Results from our study showed lack of agreement between different bioimpedance devices; direct comparison of ECW, ICW, and ECW/TBW between different devices should be avoided and clinicians should use the same device to track the fluid status in their HD population in a longitudinal direction., (© 2022 International Society for Hemodialysis.)

Maternal size, weight gain in pregnancy, fetal gender, environment and gestational age are known determinants of birth weight. It is not clear which component of maternal weight or gained weight during pregnancy influences birth weight. We evaluated the association of maternal total body water measured by the deuterium dilution technique (TBW-D 2 O) at 17 and 34 weeks of gestation with birth weight. A secondary aim was to examine the utility of bioimpedance spectroscopy (BIS) to determine total body water (TBW-BIS) in pregnancy. At 17 and 34 weeks of pregnancy, ninety-nine women (fifty-one rural and forty-eight urban) from Pune, India had measurements of body weight, TBW-D 2 O, TBW-BIS and offspring birth weight. At 17 weeks of gestation, average weights for rural and urban women were 45⋅5 ± 4⋅8 (sd) and 50⋅7 ± 7⋅8 kg ( P < 0⋅0001), respectively. Maternal weight gains over the subsequent 17 weeks for rural and urban women were 6⋅0 ± 2⋅2 and 7⋅5 ± 2⋅8 kg ( P = 0⋅003) and water gains were 4⋅0 ± 2⋅4 and 4⋅8 ± 2⋅8 kg ( P = 0⋅092), respectively. In both rural and urban women, birth weight was positively, and independently, associated with gestation and parity. Only for rural women, between 17 and 34 weeks, was an increase in dry mass (weight minus TBW-D 2 O) or a decrease in TBW-D 2 O as a percentage of total weight associated with a higher birth weight. At both 17 and 34 weeks, TBW-BIS increasingly underestimated TBW-D 2 O as the water space increased. Differences in body composition during pregnancy between rural and urban environments and possible impacts of nutrition transition on maternal body composition and fetal growth were demonstrated., (© The Author(s) 2022.)

Background: Deuterium oxide (D2O) dilution is the criterion method for total body water (TBW) measurement, but results may vary depending on the specimen type, analysis method, and analyzing laboratory. Bioelectrical impedance (BIA) estimates TBW, but results may vary by device make and model., Objectives: We investigated the accuracy and precision of TBW estimates and how measurement conditions affected the accuracy of body composition using multicompartment body composition models., Methods: Eighty collegiate athletes received duplicate TBW measures acquired from 3 BIA devices (S10, SFB7, and SOZO) and from unique D2O combinations of specimen type (saliva, urine), analysis methodology [Fourier transform infrared spectrophotometry (FTIR), isotope-ratio mass spectrometry (IRMS)], and 3 different laboratories. TBW measures were substituted into 2-compartment (2C) and 5-compartment (5C) body composition models. Criterion measures were compared using Lin's concordance correlation coefficient cutoff of poor (<0.90), moderate (0.90-0.95), substantial (0.95-0.99), and almost perfect (>0.99)., Results: Fifty-one participants (26 female) completed the protocol. Using IRMS saliva as the criterion TBW, all other measures produced a substantial or almost perfect agreement, except for SFB7 (poor) and SOZO (moderate). The 2C body composition measures using D2O and BIA produced poor agreement except for moderate agreement for lab 3 FTIR saliva. The 5C body composition measures using D2O produced a substantial agreement, whereas the BIA device S10 and SOZO had a moderate agreement, while the SFB7 had a poor agreement to the criterion. Test-retest precision varied between techniques from 0.3% to 1.2% for TBW., Conclusions: Small differences in TBW measurement led to significant differences in 2C models. The 5C models partially mitigate differences seen in 2C models when different TBW measures are used. Interchanging TBW measures in multicompartment models can be problematic and should be performed with these considerations., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Hydration of fat-free mass (FFM), defined as the ratio of total body water (TBW) to FFM (TBW/FFM), is stable at 0.739 in adult mammals. However, an increase in the TBW/FFM ratio is common in hemodialysis (HD) patients. This study aimed to evaluate the determinants of TBW/FFM and investigate its predictive value for the prognosis of all-cause mortality in HD patients. We enrolled patients undergoing maintenance HD between July 2020 and May 2021. All patients were prospectively followed until death, HD dropout, or until the end of the study (November 1, 2021). A forward stepwise multivariable linear regression analyses was performed to test the independent relationship between TBW/FMM and other clinical variables. Receiver operating characteristic (ROC) analysis was used to discriminate the TBW/FFM with respect to 180-day mortality. Of the 106 patients, 42 had elevated TBW/FFM levels. Multiple linear regression analysis revealed that the TBW/FFM ratio was significantly associated with extracellular water (ECW)/TBW (standardized regression coefficient [β = 1.131, P < .001], phase angle (PhA) [β = 0.453, P < .001], and sex (β = 0.440, P < .001). We calculated the ROC curve (AUC) of TBW/FFM, ECW, ECW/TBW, and intracellular water (ICW) to compare the discriminatory capacities of these parameters in predicting 180-day mortality. The AUC for TBW/FFM (AUC = 0.849; 95% CI, 0.745-0.953) exhibited better discriminatory potential than ECW (AUC = 0.562; 0.410-0.714), although it had a similar predictive potential as the ECW/TBW ratio (AUC = 0.831; 0.731-0.932). High TBW/FFM can be used as a valuable prognostic index for predicting all-cause mortality in patients on HD., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

The aim of the present study was to compare electrical bioimpedance variables, blood markers and functional tests based on Body Mass Index (BMI) in older women. Associations between Phase Angle (PhA) with functional tests and blood markers were also analyzed. A total of 46 independent elderly people participated in the study, and they were divided into four groups according to BMI values: Group 1 (G1, BMI < 25 kg/m2); Group 2 (G2, BMI > 25−30 kg/m2); Group 3 (G3, BMI > 30−35 kg/m2); Group 4 (G4, BMI > 35 kg/m2). In addition to the weight and height used to calculate the BMI, the following body composition variables were collected: fat mass (FM), fat-free mass, intracellular water (ICW), extracellular water (ECW), total body water (TBW) and PhA (50 kHz) through InBody S10 equipment. Functional capacity was assessed using the Fullerton battery of tests: arm-curl; chair-stand; 6 min walking test (6MWT); time up-and-go test (TUG); standing on one leg (SOOL) and take 10 foot-lines (10FL). The main results showed differences between groups in the tests: 6MWT, SOOL and 10FL between G1 vs. G3 and G2 vs. G3 (p < 0.05); ACT, AIC and AEC between G1 vs. G4 (p < 0.05); FM among all groups (p < 0.05). Negative correlations were found between PhA and the agility test in G1 (r = −0.848; p = 0.008) and G4 (r = −0.909; p = 0.005); PhA and chair-stand in G3 (r = 0.527; p = 0.044); PhA and forearm flexion in G3 (r = 0.641; p = 0.010) and G4 (r = 0.943; p = 0.001); PhA and 6MWT in G4 (r = 0.771; p = 0.042). This study found that there is a clear trend towards better functional capacities with better parameters of body composition. Although there were no differences between groups in PhA, associations were found between different functional tests with PhA, which reveals the importance of this variable as a marker of health status.

Background: In recent years, bioimpedance analysis has come to be widely used in clinical practice for dialysis patients, but there is not sufficient consensus on its significance. We aimed to examine the merits of performing bioimpedance analysis in addition to conventional evaluation methods for dry weight such as measuring human atrial natriuretic peptide (hANP), blood pressure, and cardiothoracic ratio in patients on chronic hemodialysis., Methods: Body composition of 78 hemodialysis patients was performed by using a new and more accurate segmental multifrequency bioimpedance analysis device (Seca ® medical body composition analyzer 525, Seca GmbH & Co. KG, Hamburg, Germany). Laboratory data including hANP at post-dialysis and demographic profile were collected. Statistical analysis was performed with SPSS software., Results: Mean age of the patients was 66.9 ± 12.6 years and 80.8% were males. Mean value of hANP and the ratio of extracellular water to total body water (ECW/TBW) were 61.4 ± 36.4 pg/mL and 46.1 ± 3.9%, respectively. The calculated ECW/TBW cutoff point for hANP > 50 pg/mL was 45.0%, with sensitivity of 74.4% and specificity of 64.7%. Patients with an ECW/TBW of more than 45% and hANP value of > 50 pg/mL had a higher blood pressure and cardiothoracic ratio on chest X-ray examination., Conclusions: Our results suggest that the ratio of extracellular water to total body water of more than 45% and hANP value of ≥ 50 pg/mL were overhydrated in chronic hemodialysis patients. Whether monitoring levels of these parameters has a role in the outcome including patients' survival and cardiovascular events requires further study., (© 2022. Japanese Society of Nephrology.)

Background: Maintaining low central venous pressure (CVP) is an effective strategy to reduce blood loss during hepatic resection. As an alternative to measuring CVP, which requires the placement of a central venous catheter, bioelectrical impedance analysis (BIA) is a noninvasive method recently used for monitoring volume status in critically ill patients., Methods: We investigated 192 patients who underwent hepatic resection from January 2017 to December 2020. The ratio of extracellular water:total body water (ECW/TBW), as an index of volume status, was measured using InBody S10 (Biospace, Seoul, Korea). The correlation between the ECW/TBW and CVP was determined, and their influences on operative outcomes were analyzed., Results: ECW/TBW and CVP showed a significant correlation; an ECW/TBW <0.378 correlated with a CVP <5 mmHg (R 2  = 0.839, P<0.001). Estimated blood loss (EBL) was significantly increased in patients with an ECW/TBW ≥0.378 compared to those with a ratio <0.378 (508 ± 321 vs. 324 ± 193, mL, P<0.001). Identified predictors for an EBL ≥500 mL were operative time (odds ratio [OR], 1.008; 95% confidence interval [CI], 1.001-1.015; P = 0.021) and an ECW/TBW <0.378 (OR, 0.263; 95% CI, 0.121-0.572; P = 0.001)., Conclusions: BIA can be utilized for preoperative volume assessment to minimize blood loss during hepatic resection., (Copyright © 2021 International Hepato-Pancreato-Biliary Association Inc. Published by Elsevier Ltd. All rights reserved.)

Background/objectives: Previous research has compared 2- and 3-compartment (2C and 3C, respectively) models against criterion 4-compartment (4C) models while utilizing the same body density (D b ) method for all measures. This design induces an inherent bias and obscures the added benefit of a 3C model over the simpler 2-compartment (2C) models., Purpose: The purpose of this study was to determine the effect of total body water estimates via single-frequency (SF-BIA) and multi-frequency (MF-BIA) bioimpedance analysis on body fat estimates derived from air displacement plethysmography (ADP)-derived 3C models., Subjects/methods: A sample of 95 females and 82 males (n = 177) participated in this study. Underwater weighing, dual energy X-ray absorptiometry, and bioimpedance spectroscopy were used to calculate percent fat (%Fat) via a criterion 4C model (4C CRITERION ). %Fat was predicted via 3C MFBIA (ADP and MF-BIA), 3C SFBIA (ADP and SF-BIA), and a stand-alone 2-compartment (2C) model, based upon ADP, when using Siri and Brozek body density conversion formulas (2C SIRI and 2C BROZEK . respectively)., Results: The standard error of estimate (SEE) was lowest for 3C SFBIA when evaluated in females and males (2.72% and 2.31%, respectively) and highest for 2C SIRI (3.98% and 3.84%, respectively). Similarly, the total error (TE) for females and males was lowest for 3C SFBIA (3.21% and 2.67%, respectively) and highest for 2C SIRI (4.58% and 4.48%, respectively) and 2C BROZEK (4.65% and 4.33%, respectively)., Conclusions: Results suggest that SF-BIA and MF-BIA can improve the estimation of %Fat, beyond simpler 2C models, when integrated with ADP in a more advanced 3C model. Furthermore, the present study revealed that 3C SFBIA was the best overall prediction model based upon TE values. The current study results support the integration of ADP and bioimpedance technology as part of a 3C model for the improvement of %Fat estimates over simpler 2C models., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: As hemodialysis is administered with the patient lying down, the distribution of body fluid is stable in the lying position, which is why this position is recommended for bioimpedance analysis (BIA). Although the InBody S10 is widely used for hemodialysis patients in the lying position, clinicians must make the measurements in person. In contrast, patients can use the InBody 770 to obtain measurements by themselves in the standing position, which may be more convenient. Therefore, this study compared the measurements of hemodialysis patients' estimated target weight and ECW/TBW obtained lying down using the S10 to those obtained in the standing position using the 770., Methods: This study was conducted among maintenance hemodialysis patients at Chuncheon Sacred Heart Hospital in October 2020. Measurements from 56 patients before and after hemodialysis were obtained using the 2 machines. Each (S10 or 770) estimated target weight, both pre- and post-hemodialysis, was considered ideal when the ECW/TBW ratio was 0.380. R 2 was calculated and the Bland-Altman test was performed., Results: The patients' median age was 64 years old, and 51% were men. The actual ultrafiltration was 2 kg, and the mean TBW change measured using the InBody devices was 1.5 L (R 2  = 0.718) for the S10 and 1.7 L (R 2  = 0.616) for the 770. The estimated target weight at pre- and post-hemodialysis showed a remarkably high correlation with the patients' actual pre- and post-hemodialysis weight (R 2  > 0.095). The correlation between these measurements (lying vs. standing) before and after hemodialysis was also very close (R 2  = 1.0000). In addition, ECW/TBW had a good correlation (R2 ≥ 0.970) The Bland-Altman test of dry weight and ECW/TBW yielded similar results., Conclusions: This study showed that patients' estimated target weights in the lying position using the InBody S10 device and in the standing position using the InBody 770 device were consistent in both pre- and post-hemodialysis states., (© 2022. The Author(s).)

The aim of this research was to evaluate the relevance of using deuterium oxide ( 2 H 2 O) and bio-impedance analysis (BIA) to assess size and function of the interstitium for urological research. Nineteen volunteers were recruited to this prospective trial combining ingestion of 2 H 2 O and BIA. Blood samples were obtained every 10 min after ingestion of 2 H 2 O. Urine was collected before and after the experiment. BIA was performed every 5 min. Body position was alternated to study the effect on fluid distribution. First order kinetics were assumed for the uptake of 2 H 2 O from the gastrointestinal tract to the blood. Sex seemed to have an influence with a significantly slower exchange for women ( p  = 0.041, men: 0.052 min -1 , women: 0.038 min -1 ). Impedance measured in legs (men: p  = 0.012, women: p  = 0.008) and trunk (both p  < 0.001) decreased significantly with posture change. These changes probably reflect the orthostatic redistribution of fluid with an increase of fluid in both trunk and legs. Both methods were tested and found to be useful for further urological research. Significant gender differences in 2 H 2 O uptake dynamics from the gastrointestinal pool were observed. An impact of posture changes on the electrical impedance measured was observed.

Observational hemodialysis (HD) studies report an association between hyponatremia and increased mortality. As volume overload is also associated with mortality, we wished to determine whether hyponatremia is linked to increased extracellular water (ECW). We measured ECW, total body water (TBW) and body composition predialysis with multifrequency bioimpedance, arm strength with pinch gauge and hand grip strength (PS, HGS), standard biochemistry profiles, comorbidity and clinical frailty scores (CFS). We reviewed 324 patients, 195 (60.2%) male, mean age 62.3 ± 15.6 years. Thirty-eight (11.7%) patients were hyponatremic (sodium ≤135 mmol/L), ECW/height 2 was not different, but ECW/TBW (0.409 ± 0.016 vs. 0.402 ± 0.016, p < 0.01), C reactive protein (CRP) (9(4-6) vs. 5(2-12) g/L, p < 0.05), CFS (5(4-6) vs. 4(3-6), p < 0.05) were higher in hyponatremic patients, whereas appendicular lean mass index (8.6 ± 1.7 vs. 9.4 ± 1.8 kg/m2, p < 0.01), serum albumin (36.3 ± 5.5 vs. 38.8 ± 5.0 g/L, p < 0.01) and PS (3.7(2.7-4.7) vs. 4.7 (3.2-6.5) kg, p < 0.05)) were lower. Both serum sodium, and serum sodium after adjustment for glucose were associated with serum creatinine (β 4.26, (95% confidence limits [CL] 1.9-6.7), β 3.98 (CL 1.6-6.4), both p = 0.001, respectively) and negatively with CRP (β -0.76, [CL] -1.5 to -0.5), β -0.72 (CL -1.44 to -0.12), p = 0.036, p = 0.046, respectively) in a multivariable model. Hyponatremic HD patients did not simply have an increased ECW, as the increased ECW/TBW and ECW/ICW ratios were more likely secondary to loss of muscle mass and strength, associated with increased CRP and reduced albumin, suggesting that hyponatremia is associated with inflammation, loss of muscle mass and increasing frailty., (© 2021 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.)

Introduction: The bioimpedance spectroscopy (BIS) method is used in individual patients requiring body fluid volume measurement. In a hemodialysis facility, however, regular screening of body fluid volumes is also necessary. Such screening, by kinetic modeling, may become possible by calculating distribution volumes of urea and uric acid from regular blood test results., Objective: The aim is to compare uric acid distribution volumes with BIS-extracellular volume, urea distribution volume with BIS-total body water, and difference between urea and uric acid distribution volumes with BIS-intracellular volume., Methods: We reanalyzed stored blood test data of 53 hemodialysis patients obtained together with BIS data of the same patients in our previous study., Results: Significant correlations were found between urea distribution volume and total body water predicted by the BIS method, between uric acid distribution volume and extracellular volume predicted by the BIS method, and between the difference of uric acid distribution volume from urea distribution volume and intracellular volume predicted by the BIS method. In Bland-Altman analysis, comparison of each pair showed no systematic error. The mean difference between each pair was minimal., Conclusion: Fluid volumes in different body compartments can be estimated by kinetic modeling as well as by the BIS method., (© 2022 S. Karger AG, Basel.)

Introduction: In low-flow home daily dialysis (HDD), the dialysis dose is evaluated from the total body water (TBW). TBW can be estimated by anthropometric methods or bioimpedance spectroscopy., Methods: A multicentric cross-sectional study of patients in HDD for >3 months was conducted to assess the correlation and the difference between the anthropometric estimate of TBW (Watson-TBW) and the bioimpedance estimate (BIS-TBW) and to analyse the impact on the dialysate volume prescribed., Results: Forty patients from 10 centres were included. The median BIS-TBW and Watson-TBW were 35.1 (29.1-41.4 L) and 36.9 (32-42.4 L), respectively. The 2 methods had a good correlation (r = 0.87, p < 0.05). However, Bland-Altman analysis showed an overestimation of TBW with Watson's formula, with a bias of 2.77 L. For 4, 5, or 6 sessions per week, the use of Watson-TBW increases the dialysate prescription per week by 100 L, 45 L, or 10 L, respectively, over our entire cohort. There is no increase in the volume of dialysate prescribed with the 7 sessions per week schedule., Conclusion: BIS-TBW and Watson-TBW estimation have a good correlation; however, Watson's equation overestimates TBW. This overestimation is negligible for a prescription frequency of >5 sessions per week., (© 2021 S. Karger AG, Basel.)

Background & Aims: Recently, prognostic factors for cancer cachexia patients have been reported. We hypothesized that phase angle (PhA), which is measured by bioelectrical impedance analysis (BIA), might be a promising marker for assessing the nutritional status and prognosis of cancer patients. This study aimed to evaluate the predictive utility of PhA, which is mediated by several BIA factors and other anthropometric parameters, such as calf circumference, for the prognosis of cancer cachexia patients., Methods: Consecutive patients (114, both outpatients and inpatients) with an unselected stage of cancer cachexia were recruited between July 2018 and December 2019 in Fujita Health University Hospital for this retrospective cohort study. Their mean age was 74.0 years (standard deviation, 8.5); among the total, 70 were men and 44 women. A time-dependent Cox proportional-hazards regression analysis (adjusted for age and sex) was performed to assess the following: 1) the association between potential mediators and mortality; 2) the association between five PhAs and statistically significant mediators from 1); and 3) the association between the five PhAs and mortality. Finally, Kaplan-Meier survival curves were constructed and compared between the two groups based on the patients' median baseline ratio of extracellular water (ECW) to total body water (TBW) using a log-rank test., Results: The ECW/TBW ratio (hazard ratio [HR] per 1-interquartile range [IQR] increase: 2.87; 95% confidence interval [CI]: 1.46, 5.46; p < 0.001) and skeletal muscle mass index (HR per 1-IQR increase: 0.67; 95% CI: 0.51, 0.89; p = 0.001) were associated with mortality. All five PhAs were associated with the ECW/TBW ratio (p < 0.001). Before adjustment for the ECW/TBW ratio, all five PhAs were associated with mortality (p < 0.001); only the association of the PhAs of the left arm and the trunk retained the statistical significance after adjusting for confounders (p < 0.05). The median survival times in the low (370 days; 95% CI: 168, not calculated) and high ECW/TBW groups (101 days; 95% CI: 61, 219) differed significantly (p < 0.001)., Conclusions: The association between PhA and mortality in cancer cachexia patients was largely mediated by the ECW/TBW ratio. We believe that adjusting PhA for the ECW/TBW ratio may improve the prognostication of cancer patients with cachexia, ultimately improving their palliative care., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to disclose., (Copyright © 2021 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.)

Purpose: The primary purpose of this study was to clarify the occurrence of sites of edematous changes using the measured circumferences of the thigh and lower leg via three-dimensional (3D) body scanning. The secondary purpose was to determine the relationship between the volume changes using 3D body scanning and the resistance changes as indicator of extracellular water (ECW) via segmental-bioelectrical impedance spectroscopy (S-BIS). Methods and Results: Fifteen healthy women participated. Limb circumferences were measured using 3D body scanning at 10% intervals between 50% and 80% in the thigh circumference and between 0% and 80% in the lower leg circumference. The resistance of the ECW component (R ECW ) and total body water (R TBW ) was measured using S-BIS in the thigh and lower leg segments. These measurements were conducted at baseline and 6 hours postobservation. A paired t -test was conducted for the differences in these parameters, and the effect sizes (ESs) were calculated using Cohen's d . Correlations between changes in segmental volume and R ECW were analyzed. Measurement-site circumferences and segmental volume significantly increased in the lower leg at postobservation but not in the thigh. The ES of circumference changes in the lower leg's central region were larger (ESs were 0.40-0.71 at 30%-50%) than in other regions. A significant correlation was observed between changes in segmental volume and R ECW of the lower leg (ρ = -0.79, p  < 0.001). Conclusions: Assessing the circumference using 3D body scanning, we found the edematous changes to be significant in the lower leg's central regions. Moreover, volumetry using 3D body scanning can detect edematous change in the lower leg.

Accurate human provenancing using stable isotopes depends directly on solid understandings of the geographic and individual factors affecting isotope variability and incorporation into human tissues. Transfer of isotopic, and therefore spatial, information between environmental water and biological tissues is mediated by the isotopic composition of body water. Thus, there is a need to study body water isotope ratios at a population level and over a large isotopic and geographic range. We evaluated oxygen (δ 18 O bw ) and hydrogen (δ 2 H bw ) isotope values of body water from 72 volunteers in 10 different cities across the US, and over a 5-10-day period. We analyzed covariates (e.g., water intake, physical activity, biometrics, gender) that might explain individual stable isotope ratio variations and tested a predictive model that incorporates the δ-values of drinking water, food, and O 2 as well as individual variables to predict the δ-values of body water. The individual variability in body water isotope values overtime (mean 0.3‰ for δ 18 O bw and 2.3‰ for δ 2 H bw ) was lower than the intra-city variability (mean 0.9‰ for δ 18 O bw and 6.9‰ for δ 2 H bw ). Body water isotope values differed among cities (ANOVA: δ 18 O bw F = 97.2, p < 0.001; δ 2 H bw F = 176.2, p < 0.001). However, significant overlap among some cities with different drinking water was discovered. We detected significant covariation of measured drinking water and human body water isotope values (both isotope systems R 2 ≥ 0.89, p < 0.001) and small but significant effects of the average daily exercise and amount of fluid intake. The differences between measured and model-predicted body water values (mean 0.12 ± 1.2‰ for Δδ 18 O and -1.2 ± 8.2‰ for Δδ 2 H) were statistically indistinguishable from zero (Δδ 18 O t = -0.751, p = 0.45; Δδ 2 H t = 1.133, p = 0.26). Here we show that community level variation exists in the δ 18 O bw and δ 2 H bw values and the primary drivers are the regional differences in drinking water isotopes. Consistency of the body water isotope composition over the study period suggests that tissues would incorporate a stable isotope signal over time. The amount of drinking water and physical activity influence body water values, while the variation in the isotopic values of food may contribute to regional level variability, but that still remains to be assessed further. The human body water model provides accurate estimates for measured values, capturing and reproducing the main features of the body water isotope variation across space., Competing Interests: Declaration of Interest The authors declare no conflicts of interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)