Search

Shaojie Bi,1 Juan Zhang,1 Ning Wei,2 Qingbo Zhou,3,4 Chunyan Wang3 1Department of Cardiology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People’s Republic of China; 2Department of Information Center, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People’s Republic of China; 3Department of Geriatrics, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People’s Republic of China; 4School of Nursing and Rehabilitation, Cheeloo College of Medicine, Shandong University, Jinan, People’s Republic of ChinaCorrespondence: Chunyan Wang, Email 201062013735@email.sdu.edu.cnIntroduction: Anemia, characterized by low hemoglobin or erythrocyte levels, is a significant global health issue with severe implications for public health. Recent studies have explored the potential link between anemia and 25-hydroxyvitamin D [25(OH)D], yet the precise mechanisms remain unclear. This study aims to clarify the possible causal relationship between 25(OH)D levels and anemia risk.Methods: We conducted a comprehensive investigation combining observational and Mendelian randomization (MR) analyses. The observational study included detailed demographic, comorbidities, and laboratory data collected from 7160 hospitalized patients in China. For the MR analysis, genetic polymorphisms were utilized to assess causal effects.Results: Observational analysis revealed an inverse relationship between 25(OH)D levels and the risk of anemia, with stratified analysis indicating a nonlinear association and a threshold of 48.716 nmol/L. The MR analysis confirmed a protective causal relationship between higher 25(OH)D levels and a reduced risk of anemia. Bidirectional MR analysis found no evidence that anemia influences 25(OH)D levels.Discussion: This study provides strong evidence of a causal link between increased 25(OH)D levels and a lower incidence of anemia. The findings highlight the potential role of vitamin D in anemia prevention, supporting the need for further research into vitamin D supplementation as a strategy to reduce anemia risk.Conclusion: Our findings support the hypothesis that higher 25(OH)D levels are causally associated with a reduced risk of anemia, suggesting vitamin D’s potential role in anemia prevention and public health strategies.Keywords: anemia, 25-hydroxyvitamin D, Mendelian randomization

Abstract Background Vitamin D deficiency has been linked to poor muscle function, cartilage degeneration, and the development of knee osteoarthritis. However, the impact of serum 25-hydroxyvitamin D [25(OH)D] level on quadriceps muscle strength remains inconclusive, largely due to variations in study designs, differences in study populations, and the influence of confounding factors such as co-supplementation with other vitamins. The existing literature presents mixed findings, highlighting the need for a comprehensive evaluation of the available evidence. Purpose This systematic review and meta-analysis aim to summarise. Study design Systematic review; Level of evidence, 4. Methods Searches were conducted using Medline (Ovid), Embase (Ovid), CINAHL (EBSCOhost), and SPORTDiscus (EBSCOhost), which aimed to summarise recent (published after 2000 and before March 1st, 2024) studies reporting the effects of serum 25(OH)D levels on quadriceps strength. Appraisal tool for Cross-Sectional Studies (AXIS) for cross-sectional studies and Quality in Prognosis Studies (QUIPS) for longitudinal studies. Results from the AXIS and QUIPS tools were used for GRADE quality assessment. The review was carried out using PRIMSA guidelines and registered in PROSPERO (ID: CRD42022313240). Results Four hundred studies were screened and 28 studies with 5752 participants were included. 28 published studies (24 cross-sectional and 4 longitudinal) were identified. Key results supported the significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength at 180°/s in elderly and athletic populations with a correlation coefficient of 0.245 (95%CI: 0.078–0.398, p = 0.004). However, no significant correlation was found with isometric quadriceps strength or isokinetic strength at 60°/s (r = 0.190, p = 0.085). There was only a weak negative correlation with MVC. Conclusion This review found a statistically significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength. This has important clinical implications, especially in the elderly cohort, with higher 25(OH)D levels being associated with a reduced incidence of falls and fragility fractures.

Abstract The aim of this study was to evaluate the serum level of 25-hydroxyvitamin D (25(OH)D) in children with febrile seizures (FS) in Luzhou, Sichuan Province, China, and in particular its association with gender and age. This should inform possible strategies for supplementation with vitamin D, and hence for prevention of FS in the local pediatric population. The Febrile seizures group consisted of 747 children hospitalized with FS at the Southwest Medical University Affiliated Hospital from January 2020 to January 2024. The healthy control group was comprised of 750 children aged from 0 to 8 years who underwent health checkups during this period. The serum 25(OH)D level was analyzed in relation to gender and age to explore its association with FS. The median serum vitamin D level in the FS group (28.8 ng/mL; IQR 21.64, 33.64) was significantly lower than in the healthy control group (37.51 ng/mL; IQR 31.05, 37.51). The incidence of vitamin D deficiency in the FS group was 10.8%, which was significantly higher than in the healthy control group (P

Mass spectrometry analysis has been applied in many important diagnostic fields of laboratory medicine. However, there is little literature to guide quality management systems for LC-MS/MS methods. In this study, LC-MS/MS 25-hydroxyvitamin D (25(OH)D) was used as an example to establish internal quality control strategies to ensure the accuracy of clinical vitamin D results. A total of 141 batches of samples were analyzed. Sample internal standard peak area variability, ion pair ratio, and physical examination population data were monitored as quality control strategies for 25(OH)D results. The analytical performance was evaluated by calculated Sigma metrics. Applying our quality control strategies, several abnormal data were monitored in the routine analysis. The daily peak area CV of 25(OH)D fluctuated within a certain range. By selecting P99 CV as the control target, two abnormal batches were found. The ratio of 25(OH)VD3 ion pairs was relatively stable. Among them, batch20230120 had a high CV value, which may be due to the bias caused by the limited number. According to the physical examination data, batch20220913 and batch20220919 exceeded the alarm limit. Sigma level of 25(OH)VD3 in the laboratory was 6.52, which achieved "excellent" performance. In conclusion, we established comprehensive quality control strategies for the determination of 25(OH)D by LC-MS/MS, which has high analytical performance and can provide more accurate reports for the clinic., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

ObjectiveTo investigate the levels of 25-hydroxyvitamin D [25 (OH) D] and its influencing factors in women during mid-pregnancy, and to provide an evidence for improving the vitamin D deficiency in pregnant women.MethodsA total of 220 pregnant women in the second trimester of pregnancy who underwent regular prenatal examinations at the Tianjin Binhai New Area Maternal and Child Health and Family Planning Service Center from February 2022 to February 2023 were selected as the research subjects. Basic clinical data of the pregnant women were collected. A 25 (OH) D level of ≥30 μg·L-1 was considered sufficient, while a level of

Abstract Background We aimed to probe the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cause-specific mortality among patients with gout and hyperuricemia (HUA). Methods The study included 1169 gout patients and 7029 HUA patients from the National Health and Nutrition Examination Survey (NHANES) 2007–2018 and 2001–2018, respectively. The association between serum 25(OH)D and mortality was evaluated by Cox proportional hazard and restricted cubic spline models. Results Among participants with gout and HUA, the weighted mean concentrations of serum 25(OH)D were 71.49 ± 30.09 nmol/L and 64.81 ± 26.92 nmol/L, respectively. Vitamin D deficiency occurred in 29.68% of gout patients and 37.83% of HUA patients. During 6783 person-years of follow-up among gout patients, 248 all-cause deaths occurred, among which 76 died from cardiovascular disease (CVD) and 49 died from cancer. 1375 HUA patients were recorded for all-cause mortality during 59,859 person-years of follow-up, including 427 CVD deaths and 232 cancer deaths. After multifactorial adjustment, per one-unit increment in natural log-transformed 25(OH)D was associated with lower risk of 55% all-cause mortality and 61% CVD mortality among gout patients, and a 45% reduced risk of cancer mortality among HUA patients. Restricted cubic splines showed a U-shaped relationship with all-cause and CVD mortality among HUA patients, with inflection points of 72.7 nmol/L and 38.0 nmol/L, respectively. The results were robust in subgroup and sensitivity analyses. Conclusions Serum 25(OH)D was negatively linearly correlated with mortality among gout patients, whereas U-shaped correlated with mortality in HUA patients. These results indicate that adequate vitamin D status could prevent premature death.

Background: The reference intervals (RIs) is defined as the central 95 % range of reference values from healthy individuals. The establishment of appropriate medical RIs for specific populations is crucial for accurate diagnosis and treatment of disease. However, the RIs for 25-hydroxyvitamin D (25(OH)D) in Chinese pediatric individuals are currently not available. This retrospective study aimed to establish pediatric RIs for serum 25-hydroxyvitamin D (25(OH)D) in the Nanjing area of China. Methods: After data filtering and deletion of outliers, 133,562 serum 25(OH)D records were finally included in this study. The effects of age, sex, and season on 25(OH)D levels were assessed, and the 2.5 % and 97.5 % percentile points were applied as the lower limit and upper limit of the RIs, respectively. Results: Age-distribution analysis of serum 25(OH)D levels revealed that children aged 4–12 months old hold the highest 25(OH)D levels, and levels subsequently decreased with age while remaining relatively stable in children aged 7–15 years old. An analysis of sex-specific differences demonstrated that serum 25(OH)D levels in girls were significantly higher than those of boys 7 years old (P

Background: Thyroid disease is one of the most common illnesses in the UAE, which could be linked to vast numbers of people suffering from vitamin D deficiency. This study aimed to explore the association between serum 25(OH)D levels and thyroid function parameters in men and women with diagnosed hypothyroidism. Methods and Results: This cross-sectional observational study included 86 patients (78[90.7%] women and 8[9.3%] men) with diagnosed hypothyroidism. The patients were divided into two groups, male and female. These two groups were compared in terms of age, TSH, free-T4 (FT4), vitamin D, free-T3 (FT3), and body mass index (BMI). In addition, the correlation between levels of vitamin D and TSH was also examined in these two groups. The mean age of the patients was 27.5 years, and BMI was 28.00 kg/m2, indicating overweight. Vitamin D deficiency was found in 61(70.9%) patients and severe vitamin D deficiency in 10(11.6%) patients with hypothyroidism. 25(OH)D levels were significantly low in patients with high TSH levels, showing a weak negative correlation (r=-0.132, P=0.043). A negligible positive correlation was identified between 25(OH)D levels and FT4 r=0.089, P>0.05) and FT3 (r=0.071, P>0.05), and a negligible negative correlation with BMI (r=-0.059, P>0.05). Conclusion: There is a clear indication that vitamin D deficiency is prevalent in hypothyroid patients and that these subjects have lower levels of serum 25(OH)D. Suggesting that lower serum 25(OH)D is related to hypothyroidism and the deficiency in vitamin D plays a role in the development of the disease.

Background: Because of the pathophysiological role of vitamin D in health, there is an increased interest to check the clinical status of this vitamin. Immunochemical assays are commonly employed to determine 25-hydroxyvitamin D (25 (OH) D) in clinical laboratories and its testing could be influenced by pre-analytic and analytic issues. The aim of this study was to compare the 25(OH)D results obtained from three commonly used immunoassays in pregnant women to check a possible discrepancy between tests. Material and methods: A group of 50 pregnant women who were in their third trimester were included in this study. The quantification of serum vitamin D was performed utilizing three immunochemistry-based assays including Elecsys, VIDAS and Alegria. We also involved 21 non-pregnant volunteers to clinically assess the vitamin D status in this group of people. Results: Our findings revealed a significant inconsistency between the obtained results from three assays for serum 25(OH)D. The 25(OH)D showed higher values when measured by the Elecsys assay while the VIDAS assay had lower values compared to the other immunoassays. More notably, the 25(OH)D testing in non-pregnant subjects showed consistent results in all three immunoassays. Conclusions: The results of the 25(OH)D measurements in pregnant women should be interpreted carefully due to a great inaccuracy in immunoassay testing. There is no such disagreement in non-pregnant people. Standardization of vitamin D testing in various settings is a crucial matter for clinical laboratories.

BackgroundExisting studies investigating the impact of serum calcium (Ca), phosphate (P), 25 hydroxyvitamin D (25[OH]D), and parathyroid hormone (PTH) levels on kidney function have produced inconsistent results. Further research is needed to establish the direct causal relationship between these factors and kidney function.MethodsThe study used genome-wide association study datasets for exposure and outcome, mainly derived from the UK Biobank and CKDGen Consortium, with sample sizes ranging from 3,310 to 480,699 individuals of European ancestry. Heritability and genetic correlations among these phenotypes were assessed using linkage disequilibrium score regression (LDSC) and phenotypes with a heritability z-score

In this study, the aim is to provide a more detailed understanding of vitamin D metabolism by evaluating the correlation between 1,25-dihydroxyvitamin D (1,25(OH)2D) and 25-hydroxyvitamin D (25(OH)D) according to the variations in measurement methods and clinical conditions.

BackgroundSerum 25-hydroxyvitamin D level is associated with erectile dysfunction (ED) in observational studies. However, whether there is a causal association between them remains uncertain.ObjectiveConduct a two-sample Mendelian randomization (MR) analysis to investigate the causal effect between serum 25-hydroxyvitamin D level and ED risk.MethodGenome-wide association study (GWAS) data of serum 25-hydroxyvitamin D levels comprising 6,896,093 single nucleotide polymorphisms (SNP) from 496,949 people of European ancestry were regarded as exposure for the MR analysis. Additional GWAS data involving 9,310,196 SNPs of 6,175 European ED cases and 217,630 controls were used as outcome data. The MR-Egger, inverse variance weighted (IVW) method, weighted median, simple mode, and weighted mode were employed to evaluate causal effects, among which IVW was the primary MR analysis method. The stability of the MR analysis results was confirmed by a heterogeneity test, a horizontal pleiotropy test, and the leave-one-out method.ResultThere were 103 SNPs utilized as instrumental variables (p < 5 × 10−8). The results of MR analysis showed no causal effects of serum 25(OH) D concentration on ED risks (IVW; OR = 0.9516, 95% CI = 0.7994 to 1.1328, p = 0.5772). There was no heterogeneity and pleiotropy in the statistical models.ConclusionThe present MR study did not support a causal association for genetically predicted serum 25-hydroxyvitamin D concentration in the risk of ED in individuals of European descent.

Background: Insufficiency of omentin-1 and 25-hydroxyvitamin D serum levels is associated with obesity, which is known as a threat to health. Therefore, the aim of the present study was to examine the effect of eight weeks of Pilates exercise on the serum levels of 25-hydroxyvitamin D, omentin-1, and lipid profile in overweight women. Methods: In the present clinical study, 26 young overweight women were divided (block randomization method) into the Pilates exercise (PT, n= 13) and control group (CG, n= 13). The PT group performed Pilates exercises for eight weeks (three 60-min sessions per week). The movements started from simple and then increased in intensity and complexity based on the Borg index. The CG group had no training session for eight weeks. Blood samples were taken before the first training session and 48 hours after the last training session. Analysis of covariance was used for between-group comparisons. Results: Findings showed a significant increase in the serum levels of 25-hydroxyvitamin D (p=0.008, SD= 4.78±0.12 ng/ml, effect size= 0.243) and HDL-C (p=0.04, SD= 6.44±1.05 mg/dl, effect size= 0.168), but a significant decrease in HOMA-IR (p=0.001, SD= 1.54±0.09, effect size=0.199), cholesterol (p=0.001, SD= 16.72±3.24 mg/dl, effect size= 0.326), and triglyceride (p=0.001, SD= 2.46±0.07 mg/dl, effect size= 0.209), and no significant change in omentin-1 (p=0.65, SD= 3.01±0.08 ng/ml) and LDL-C (p=0.58, SD= 2.46±0.07 mg/dl) serum levels in the PT group compared to the CG group. Conclusion: It seems that this type of exercise training may play a critical role in controlling the health parameters and physiological status of the overweight women by having positive effects on serum levels of 25-hydroxyvitamin D and lipid profile, which are affected by body composition, weight, and fat.

The circulating vitamin D level that is optimal for health is unknown. This study aimed to examine the association between circulating vitamin D level and risk of all-cause and cause-specific mortality. This prospective cohort study included 18,797 Korean adults aged 40 years or older, living in rural areas, with no history of cancer or cardiovascular disease (CVD) at baseline. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured at baseline. Participants were followed-up from the survey date (2005–2012) until December 31, 2021. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality by baseline vitamin D level. Restricted cubic splines were used to explore the nonlinearity. The median (interquartile range) of 25(OH)D level was 55.8 (40.8–71.8) nmol/L. During a median follow-up of 14.3 years, 2250 deaths were recorded. Compared with participants with a 25(OH)D level <30 nmol/L, higher vitamin D levels (30 to < 50, 50 to < 75, and ≥75 nmol/L) were associated with a lower risk of all-cause mortality: HR (95% CI) of 0.82 (0.69–0.98), 0.74 (0.62–0.88), and 0.69 (0.57–0.84), respectively. A nonlinear relationship between vitamin D level and all-cause mortality was observed, with the risk plateauing between 50 and 60 nmol/L (p for nonlinearity = 0.009). The association was more pronounced for cancer-related mortality. HR 0.55 (95% CI: 0.39–0.77) for a 25(OH)D level ≥75 nmol/L compared with <30.0 nmol/L. Low vitamin D levels were associated with increased CVD mortality in men. Vitamin D level was inversely associated with all-cause and cause-specific mortality in middle-aged and older adults. Maintaining a serum 25(OH)D level of approximately 50–60 nmol/L may contribute to longevity and warrants further investigation. [ABSTRACT FROM AUTHOR]

BackgroundToxoplasma gondii (T. gondii) is a widespread zoonotic parasite transmitted through contaminated food or water. It poses a significant public health threat, especially to pregnant women and immunocompromised individuals. 25-Hydroxyvitamin D [25(OH)D] plays a critical role in regulating both innate and adaptive immune responses, particularly in its anti-infective capacity. However, the relationship between serum 25(OH)D concentrations and T. gondii infection remains uncertain.MethodsWe analyzed the data from the National Health and Nutrition Examination Survey (NHANES) spanning 2009–2014 to explore the association between serum 25(OH)D concentrations and T. gondii infection. Extensive demographic, comorbidity, and dietary data were collected. The status of T. gondii infection was determined using serum anti-IgG antibodies. Serum 25(OH)D levels were measured using ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). In addition, weighted logistic regression and restricted cubic spline analyses were performed.ResultsOur analysis included 10,157 participants (mean [SE] age, 45.38 [0.39] years; 49.73% female) who met the inclusion criteria. Serum 25(OH)D levels were categorized into quintiles, with the second quintile serving as the reference group. The final model, adjusted for age, sex, race, education level, poverty income ratio, body mass index, smoking status, hypertension, diabetes, chronic kidney disease, depression, physical activity, alcohol intake, seasonal testing, and dietary vitamin D, revealed the following adjusted odds ratios (ORs) for the quintiles: 0.75 (95% confidence interval [CI]: 0.60–0.93) for the first, 0.87 (95% CI: 0.69–1.10) for the third, 0.75 (95% CI: 0.58–0.95) for the fourth, and 0.66 (95% CI: 0.49–0.91) for the fifth. Additionally, a restricted cubic spline analysis revealed an inverted U-shaped relationship between serum 25(OH)D and T. gondii infection, with an inflection point at approximately 51.29 nmol/L. Odds ratios to the left and right of the inflection point were 1.17 (95% CI: 1.03–1.32) and 0.94 (95% CI, 0.90–0.98) per 10 nmol/L, respectively.ConclusionOur study uncovers an inverted U-shaped relationship between serum 25(OH)D concentrations and T. gondii infection, with an inflection point around 51.29 nmol/L.

BackgroundNutritional support has been identified as a potential intervention for cognitive frailty; however, the association between 25-hydroxyvitamin D [25-(OH)D], vitamin B12, and cognitive frailty remains ambiguous.MethodsThis study utilized data from two cycles (2011–2012, 2013–2014) of the National Health and Nutrition Examination Survey (NHANES) to investigate this relationship. The researchers constructed a 41-item frailty index encompassing diverse aspects of physical functioning, psychological evaluation, and medical conditions, and evaluated each participant individually. The study utilized Spearman's rank correlation coefficient and univariate ordered logistic regression to assess the relationships between variables and cognitive frailty. Recursive feature elimination and cross-validation methods were employed to identify the most influential variables for building and optimizing multivariate ordered logistic regression models. Subgroup analyses and interaction tests were further conducted to validate the identified correlations.ResultsThe findings of this study confirm a negative linear correlation between 25-(OH)D levels and cognitive frailty in older adults. Specifically, a one-unit increase in 25-(OH)D levels was associated with a 12% reduction in the risk of cognitive frailty. The result was further supported by subgroup analyses and interaction tests.ConclusionThe existence of a negatively correlated linear association between 25-(OH)D levels and cognitive frailty in older adults is plausible, but further rigorously designed longitudinal studies are necessary to validate this relationship.

ObjectiveThis study aimed to investigate the correlation between serum 25-hydroxyvitamin D (25(OH)D) levels and retinopathy of prematurity (ROP) in premature infants one month after birth.MethodsPreterm infants (gestational age

BackgroundPrevious studies on the liner associations between serum 25-hydroxyvitamin D [25(OH)D] levels and lipid profiles revealed ambiguous findings. The current study therefore tried to elucidate the possible non-linear associations between 25(OH)D and lipid profiles.MethodsThis study involved 8,516 adult participants (aged 18–74 years, males N = 3,750, females N = 4,766) recruited from the Dalian health management cohort (DHMC). The risk (OR) for specific dyslipidemias was estimated across the serum 25(OH)D levels and the cut-off value for serum 25(OH)D were determined by using logistic regression, restricted cubic spline, and piecewise linear regression methods, adjusted for age, sex, season, and ultraviolet index.ResultsIn this study, a high prevalence of 25(OH)D deficiency was observed in the participants (65.05%). The level of 25(OH)D showed the inverse U-shaped correlations with the risks (ORs) of abnormal lipid profile, with inflection points observed at 23.7 ng/ml for hypercholesterolemia, 24.3 ng/ml for hypertriglyceridemia, 18.5 ng/ml for hyper-low-density lipoprotein cholesterolemia, 23.3 ng/ml for hypo-high-density lipoprotein cholesterolemia, 23.3 ng/ml for hyper-non-high-density lipoprotein cholesterol, and 24.3 ng/ml for high remnant cholesterol. The stratified analyses showed that the risk for most dyslipidemias related to deficiency of 25(OH)D was particularly increased among females aged 50–74 (except for hypertriglyceridemia, where the highest risk was among men aged 50–74 years), during winter/spring or under low/middle ultraviolet index environments.ConclusionsNonlinear inverse U-shaped associations were observed between 25(OH)D levels and abnormal lipid profile. The risk was particularly increased among females aged 50-74, during winter/spring period or under lower ultraviolet index environments. In vitamin D deficient subjects [25(OH)D

Exposure to ultraviolet (UV) radiation from the sun has both harms and benefits for human health. The best-known benefit of sun exposure is the generation of vitamin D within the skin and the best-known harm is malignant skin cancer. Australia and New Zealand have very high ambient UV radiation, resulting in high rates of skin cancer incidence and mortality, yet there is an appreciable prevalence of vitamin D deficiency (defined as blood 25-hydroxyvitamin D (25(OH)D) < 50 nmol/L) in both populations. The purpose of this study was to create a microsimulation model to replicate population 25(OH)D concentrations of people living in Australia and New Zealand, thus enabling the effect of different population-wide interventions to be estimated. We used large population datasets containing data on sun behaviours and socio-demographic variables, and environmental data on UV radiation, ozone, and solar zenith angle. Latitude, weather and time of day were accounted for. We simulated the conversion of daily UV radiation to a standard vitamin D dose (SDD) (100 J/m2 vitamin D-weighted UV) and monthly accumulation of SDD to 25(OH)D concentration. The model was calibrated to match the seasonal prevalence of vitamin D deficiency. This report describes the Sun Exposure (SUNEX) microsimulation model, its development, data inputs and calibration against population prevalence of vitamin D deficiency.

Zhenghui Xu,1,&ast; Junli Zhang,1,&ast; Shoukui Xiang,1,&ast; Fei Hua,1 Lu Chen1,2 1Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Soochow University, Changzhou, 213003, People’s Republic of China; 2Department of Clinical Nutrition, The Third Affiliated Hospital of Soochow University, Changzhou, 213003, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Fei Hua, Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Soochow University, Changzhou, 213003, People’s Republic of China, Tel +86 0519-68870000, Email huafei1970@suda.edu.cn Lu Chen, Department of Clinical Nutrition, The Third Affiliated Hospital of Soochow University, Changzhou, 213003, People’s Republic of China, Tel +86 0519-68870424, Email cl2324@czfph.comPurpose: To explore the association between the water distribution in the human body and 25-hydroxyvitamin D among patients with type 2 diabetes mellitus (T2DM), and to analyze whether water distribution is a mediator between vitamin D and T2DM complications.Patients and Methods: In total, 533 T2DM inpatients were included from August 1, 2016 to April 1, 2023. Water distribution indicators, whether from the whole body, arms, trunk, or legs, were measured to calculate the association with vitamin D using linear regression analysis. Subgroups based on age, sex, body mass index, and macrovascular complications were established to clarify changes in the association between vitamin D and water distribution in different populations. Mediation analysis was applied to evaluate the correlation between vitamin D, water distribution, and T2DM complications.Results: There was a negative correlation between 25-hydroxyvitamin D and the ratio of extracellular water (ECW)/total body water (TBW) both in the whole body (P=0.045, β=− 0.008) and in certain parts. A U-shaped restricted cubic spline curve further presented an inflection point (approximately 23 ng/mL 25-hydroxyvitamin D) in the relationship between 25-hydroxyvitamin D and the ECW/TBW of the whole body. A negative correlation was observed between ECW/TBW and vitamin D in the obese subgroup (P=0.015, β=− 0.038). In the total effect of vitamin D on diabetic nephropathy (DN), the mediation effect of ECW/TBW accounted for 15.44%.Conclusion: A correlation between vitamin D and water distribution was observed, and a high ECW/TBW was one of the pathways through which low vitamin D levels might affect DN.Keywords: 25-hydroxyvitamin D, ECW/TBW, type 2 diabetes mellitus, diabetic nephropathy

Abstract Background The relationship between serum vitamin D status and urinary leakage (UL) among middle-aged females needs to be further studied. The aim of this study was to evaluate the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with UL among American females ages 45 years and over. Methods Seven cycles of the National Health and Nutrition Examination Survey (NHANES) with self-report UL data, were used. A total of 9525 women aged 45 years and older were enrolled in this study. Univariate and multivariate logistic regression models and the smooth curve fitting were utilized to analyze the association between clinical UL and serum 25-hydroxyvitamin D [25(OH)D] concentrations. Results A non-linear relationship between serum 25(OH)D concentrations and clinical ULwas observed. When serum 25(OH)D concentration was higher than the inflection point 63.5 nmol/L, a positive correlation was observed between serum 25(OH)D concentrations and clinical UL ([OR]: 1.007, 95%CI: 1.005–1.009, P