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KIM-1 (kidney injury molecule 1), a marker of acute kidney injury, is produced by epithelial cells of renal proximal tubules. Elevated KIM-1 levels in urine and plasma are associated with renal cell carcinoma (RCC). The aim of this study was to compare the significance of non-normalized uKIM-1 values and those normalized to urine creatinine, as urinary biomarkers in RCC. The uKIM-1, urine creatinine and their ratio (uKIM-1/Cre) were studied in 118 RCC patients and 58 apparently healthy subjects. The median of uKIM-1 in the healthy group was 0.71 ng/ml (1st and 3rd quartiles were 0.35 and 1.23, respectively) and in RCC patients it was 2.36 (1.43; 5.93) ng/ml. The medians of uKIM-1/Cre were 0.77 (0.49; 1.18) and 2.42 (1.41; 4.61) ng/mgCre, respectively. Stage I RCC is statistically significantly different from stages II-III and stage IV using uKIM-1/Cre values (p = 0.0056 and p = 0.0012, respectively); using uKIM-1 values significant differences occur only when comparing stages I and IV (p = 0.015). In both healthy individuals and RCC patients, uKIM-1/Cre levels were slightly lower in subgroups younger than 50 years than in subgroups older than 50 years, whereas a similar trend was observed for uKIM-1 only in patients. In healthy men and male patients, uKIM-1 levels were higher than in the corresponding groups of women (the differences were not statistically significant), but the use of uKIM-1/Cre values eliminated the gender differences. A high correlation was found between the concentrations of uKIM-1 and urine creatinine in three healthy subjects followed up for 3 weeks (Spearman’s correlation coefficients were 0.758, 0.825 and 0.933, respectively). The data obtained are clear evidence of the need for normalization uKIM-1 to urine creatinine in RCC patients.

Creatinine excretion is widely used as a method to evaluate the adequacy of urine collection in different clinical settings. Many factors influence its elimination, such as protein intake, exercise, muscle mass, age, and sex, among many others. As 24-hour urine collections can be cumbersome, several equations have been developed to aid clinicians to correctly interpret results derived from them. In this review article, we report the factors that can modify creatinine excretion and we evaluate the accuracy of different published equations to estimate 24-hour urine creatinine excretion.

Objective: Similar to pregnant women, women taking an oral contraceptive (OC) might have elevated iodine requirements due to the altered hormonal state. This is the first study aimed at investigating the prevalence of iodine deficiency and possible influences of OC intake on urine creatinine and iodine levels in young women. Methods: One hundred fifty-five women between the age of 18 and 35 years (62 taking an OC and 93 controls) participated in a cross-sectional pilot study at the Medical University of Vienna, which included a 1-spot urine sample and a questionnaire on OC intake as well as a food questionnaire. Results: The median urinary iodine concentration (UIC) in this study was 68 μg/L (41, 111 μg/L) suggesting an inadequate iodine status in the women according to the WHO guidelines. Median UIC (OC: 89 μg/L, IQR 55–120; control: 59 μg/L, IQR 39–91, p = 0.010) and urine creatinine (OC: median = 99.0 μg/L, IQR 74.9–175.5; control: 77.0 μg/L, IQR 49.6–147.2, p = 0.030) levels were significantly higher in OC women than in the control group. UIC corrected for urine creatinine was comparable between both groups. Conclusion: With similar creatinine-corrected UICs in both groups, OC intake might not have a significant impact on iodine status. However, the low median UIC in a vulnerable group of young women potentially conceiving in the following years points at the necessity of optimizing the iodine intake in the Austrian population and reiterates the insufficiency of the current iodine supplementation measures.

Erroneous conclusions may result from normalization of urine cadmium and N-acetyl-β-D-glucosaminidase concentrations ([Cd]u and [NAG]u) to the urine creatinine concentration ([cr]u). In theory, the sources of these errors are nullified by normalization of excretion rates (ECd and ENAG) to creatinine clearance (Ccr). We hypothesized that this alternate approach would clarify the contribution of Cd-induced tubular injury to nephron loss. We studied 931 Thai subjects with a wide range of environmental Cd exposure. For x = Cd or NAG, Ex/Ecr and Ex/Ccr were calculated as [x]u/[cr]u and [x]u[cr]p/[cr]u, respectively. Glomerular filtration rate (GFR) was estimated according to the Chronic Kidney Disease (CKD) Epidemiology Collaboration (eGFR), and CKD was defined as eGFR &lt, 60 mL/min/1.73m2. In multivariable logistic regression analyses, prevalence odds ratios (PORs) for CKD were higher for log(ECd/Ccr) and log(ENAG/Ccr) than for log(ECd/Ecr) and log(ENAG/Ecr). Doubling of ECd/Ccr and ENAG/Ccr increased POR by 132% and 168%, doubling of ECd/Ecr and ENAG/Ecr increased POR by 64% and 54%. As log(ECd/Ccr) rose, associations of eGFR with log(ECd/Ccr) and log(ENAG/Ccr) became stronger, while associations of eGFR with log(ECd/Ecr) and log(ENAG/Ecr) became insignificant. In univariate regressions of eGFR on each of these logarithmic variables, R2 was consistently higher with normalization to Ccr. Our tabular and graphic analyses uniformly indicate that normalization to Ccr clarified relationships of ECd and ENAG to eGFR.

Background and aims The low-salt diet is considered important for control of ascites in cirrhotic patients. To validate whether the spot urine sodium (Na)/potassium (K) ratio could replace 24-h urine Na (uNa) excretion in assessing low-salt diet compliance. Methods We prospectively studied 175 patients. 24-h urine collection and spot urine collection were performed. Subsequently, 24-h uNa, urine creatinine (uCr), and spot urine Na and K were assessed. A complete urine collection was confirmed based on 24-h uCr excretion levels of 15mg/kg/day for men and 10mg/kg/day for women. The area under the receiver operating characteristic (AUROC) curve analysis was performed to evaluate the feasibility of spot urine Na/K ratio in predicting 24-h uNa greater than 78mmol/day. Results Out of 175 patients, 24-h urine samples were completely collected in 57 patients only. Moreover, urine samples were not completely collected in 118 patients because their 24-h uCr excretion level was less than the established criteria. In complete urine collection group, AUROC curve for spot urine Na/K ratio in predicting 24-h uNa greater than 78mmol/day was 0.874±0.051 (P Conclusions The spot urine Na/K ratio reflects 24-h uNa, but the AUROC value obtained in this study is lower than that of a previous study. Considered the large number of patients with incomplete urine collection, validating 24-h complete urine collection criteria is necessary.

BACKGROUND Nephrotic syndrome is a common renal disease in 2-6-year-old children characterised by proteinuria, hypoalbuminemia, oedema and hypercholesterolemia. Incidence is 2-3 /1 lakh children per year. Without treatment, nephrotic syndrome in children is associated with significant morbidity and mortality. Aim of the study is to evaluate the usefulness of urine protein/urine creatinine ratio of (UP/UC) in a random and reliable test for the quantification of proteinuria. MATERIALS AND METHODS This is a prospective case control study for a period of one year i.e., from 1st July 2013 to 30th June 2014 carried out in the paediatric wards of King George Hospital, Visakhapatnam, Andhra Pradesh. A case group of 40 children suffering from nephrotic syndrome and a control group of 40 children with proteinuria due to causes other than nephrotic syndrome who fulfilled the inclusion criteria were included in the study. RESULTS A case group of 40 children between the ages of 2-12 years who were admitted with nephrotic syndrome during the study period. Males were 24(60%) and 16(40%) females. 24(60%) children presented with first episode and 16(40%) children with relapse at the time of admission. All cases presented with anasarca. 21(52.5%) children also had scrotal oedema. Oliguria was present in 39(97.5%) cases and UTI in 22 (55%) children. Regarding lab investigations, urine albumin was found to be 4+ in 36 children. Mean values of serum creatine was 0.603 mg//dl. Urine spot protein to urine creatine ratio was 6.16 in study group, whereas it was 1.01 in control group and the p value was statistically significant (0.0001). Applying tests of significance and kappa statistics, the UP/UC test in comparison with 24- hour urine protein ratio values were found to have a sensitivity of 95%, positive predictive value of 95%, specificity of 95%, positive predictive value of 95% and correlation coefficient r=0.802 and p 3 with normal renal function represents nephrotic range proteinuria.

Background: Accurate assessment of urine flow remains challenging in both inpatient and outpatient settings. We hypothesized we could derive an equation that would accurately estimate urine flow rate (eV) through derivation from other existing equations commonly used in nephrology clinical practice. Methods: The eV equation was derived using the Cockcroft-Gault and the measured creatinine clearance (CrCl = UCrV/PCr) equations. Within the African American Study of Kidney Disease and Hypertension (AASK; n = 570) and COMBINE (n = 133) clinical trials, we identified participants with concordant estimated and measured creatinine excretion rates to define a subset with highly accurate 24-h urine collections, to assure a reliable gold standard. We then compared eV to measured 24-h urine flow rates in these trials. Results: In AASK, we found a high correlation between eV and measured urine flow rate (V; r = 0.91, p < 0.001); however, Bland-Altman plots showed that eV was 9.5 mL/h lower than V, on average. Thus, we added a correction factor to the eV equation and externally validated the new equation in COMBINE. eV and V were again highly correlated (r = 0.91, p < 0.001), and bias was improved (mean difference 5.3 mL/h). Overall, 80% of individuals had eV that was within 20% of V. Conclusions: A simple equation using urine creatinine, demographics, and body weight can accurately predict urine flow rate and may have clinical utility in situations where it is difficult to accurately measure the urine flow rate.

Background Serum creatinine concentrations are higher in Greyhounds when compared with nonsighthound breeds. Greyhounds might also have higher urine creatinine concentrations compared with other breeds, which could affect urine protein-to-creatinine ratio (UPC) references. Objectives We aimed to determine the UPC reference intervals (RIs) in healthy nonracing Greyhounds and compare this with UPC values in a group of healthy nonsighthounds and with the current International Renal Interest Society (IRIS) guidelines. Methods The study used an observational cross-sectional design, involving clinically healthy, nonracing Greyhounds (n = 98) and nonsighthound dogs of similar weight, age, and sex (n = 24). Packed cell volumes, total solids, urine protein concentrations, serum and urine creatinine concentrations, urine specific gravity (USG) measurements, and UPCs were determined. Linear regression was used to compare urine creatinine and urine protein concentrations, relative to the USG measurements, between Greyhound and nonsighthound groups. Greyhound UPC RIs were determined using nonparametric methods and compared with UPC values in nonsighthounds and current IRIS guidelines. Results Mean urine creatinine concentrations, adjusted for USGs, were approximately 22% higher in Greyhounds compared with nonsighthounds (P = .002). Mean urine protein concentration (P = .46) and UPC (P = .1) were not significantly different between Greyhounds and nonsighthounds. The upper limit of the Greyhound UPC RI was 0.20 or 0.42, depending on whether strict or moderate exclusion criteria were applied, respectively. Conclusions Greyhounds have higher urine creatinine concentrations than nonsighthounds. Although the suggested RI for UPCs in Greyhounds is slightly lower than the cut-offs recommended in generic canine IRIS guidelines, this difference is not likely to be clinically significant.

Increased urine albumin concentration (UALB) or urine albumin-to-creatinine ratio (UACR) at admission has been associated with systemic disease and increased morbidity and mortality in critically ill canine patients. The objective of this study was to assess the prognostic value of UALB and UACR for the survival, as well as for the development and duration of systemic inflammatory response syndrome (SIRS) in puppies with canine parvoviral enteritis (CPVE). Unvaccinated puppies, aged 1-12 months with confirmed CPVE, hospitalized for ≥5 days were included. Urine was collected at admission via cystocentesis; albumin was measured immunoturbidimetrically and creatinine spectrophotometrically. The presence of SIRS was daily evaluated. Statistical analysis was conducted using R language. Twenty-six dogs were enrolled; 12/26 (46%) developed SIRS during hospitalization, while 5/26 (19%) died. A significant correlation was found between UALB and UACR (ϱ=0.868, p0.05). SIRS duration was significantly correlated with UACR (ϱ=0.427, p=0.030), but not with UALB (ϱ=0.386, p=0.052). The non-survivors had higher median UALB [0.6 (0.1-12.7) mg/dL] and UACR [19.6 (0.7-2,093) mg/g] compared to survivors [UALB= 0.2 (0-1.5) mg/dL, UACR= 2.3 (0-16.9) mg/g], but the differences were non-significant (p>0.05). UACR appears to be a prognostic indicator of SIRS duration in puppies with CPVE. However, a large-scale study is warranted to confirm the usefulness of UALB and UACR for clinical risk assessment in puppies with CPVE.

Background A blood urea nitrogen to creatinine ratio (BCR) of 20 or greater indicates various physiological conditions. Whether glomerular filtration rate (GFR) estimates obtained using the Modification of Diet in Renal Disease (MDRD) study equation and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study equations are affected by a high BCR remains unknown. Methods Patients who underwent urine creatinine clearance (CrCl) and serum blood urea nitrogen (BUN) and creatinine assessments on the same day were enrolled in our study. Those with BCR of 20 or greater and less than 20 were categorized into high- and low-BCR groups. The concordance on diagnosing chronic kidney disease (CKD) stages by using urine CrCl level and serum GFR estimates was assessed. Results More disagreement in CKD stage diagnosis was observed in the high-BCR group (weighted κ = 0.600 and 0.541 for the MDRD and CKD-EPI study equations, respectively) than in the low-BCR group (weighted κ = 0.816 and 0.758, respectively). Conclusions A BCR of 20 or greater caused misestimation of the CKD stage. GFR estimates for patients with high BCR should be interpreted cautiously.

Summary: Procedure followed to detect the concentration of creatinine in serum, plasma, and urine.

BACKGROUND:Urine concentration (UC) provides clinically useful information concerning hydration status and renal function of animals. OBJECTIVES:To characterize the clinical performance of urine specific gravity measured by optical refractometry (USG-R ) or Multistix-SG urine reagent dipstick (USG-D ), urine electrical conductivity using an OAKTON Con 6 conductivity handheld meter (UEC ), urine color (UColor ) using a custom-designed 8-point color chart, and urine creatinine concentration (UCreat ) for assessing UC in dairy cattle. ANIMALS:20 periparturient Holstein-Friesian cows. METHODS:Urine was obtained by perineal stimulation or urethral catheterization and urine osmolality (UOsm , reference method), USG-R , USG-D , UEC , UColor , and UCreat determined. Diagnostic test performance was evaluated using Spearman's rho and logistic regression to determine the area under the receiver operating curve (AUC) and optimal cut point for diagnosing hypohydration (UOsm ≥800 mOsm/kg). P

Regardless of the recent advancements in the understanding of the pathophysiology of acute kidney injury (AKI), its diagnosis remains fundamentally dependent on the serum creatinine (sCr) level and urine output (UO), both of which are considered late markers of AKI, offering only a vague idea of the actual creatinine clearance (CrCl). Although not ideal, CrCl is still the most common alternative of the glomerular filtration rate (GFR) in clinical practice. It is generally accepted that early diagnosis of AKI must reveal kidney impairment before sCr increases. Much effort has been made to find tubular and glomerular markers of injury which increase (in blood and/or in urine) before the ‘official' diagnosis of AKI. Most of these markers are expensive and not widely available, especially in developing countries. Urine creatinine (CrU), the major link between sCr and UO, has been systematically ignored and clinicians are usually unaware of its value. The reasons for this are unclear, but it may be related to the lack of a reference range, dependence of its concentration value on the urine flow (which in turn is only adequately assessed with an indwelling urinary catheter) and the clinical unavailability of its counterbalance part - creatinine production. Changes in urine tend to precede changes in blood in the course of AKI development and recovery. Hence, it is important to bear in mind that changes in sCr signal renal dysfunction with a significant delay. The search for a more dynamic, ‘real-time' but pragmatic assessment of renal function, especially in patients at risk of abrupt decrease in GFR is certainly one of the most relevant focus of research in the field of AKI monitoring. Systematic CrU assessment may be highly relevant in this case.

Background The clinical importance of random urine creatinine concentration in CKD population remains undetermined. Earlier studies found that lower 24-h urine creatinine excretion was associated with the risk of ESRD and all-cause mortality among CKD patients. Methods We modeled the longitudinal trajectories of serial random urine creatinine among 4689 CKD patients enrolled in a national registry-based pre-ESRD program between 2003 and 2015 at a tertiary medical center. Other biochemical parameters including kidney function and serum albumin were regularly evaluated. Primary study outcomes were ESRD requiring maintenance dialysis and all-cause mortality. Results By group-based trajectory modeling, the urine creatinine trajectories were characterized into three patterns: (1) stable low; (2) medium; and (3) high-declining. The adjusted hazard ratio of incident ESRD and all-cause mortality increased by 6% (95% CI: 1–12%) and 9% (95% CI: 2–17%), respectively, for each 20 mg/dL reduction in baseline random urine creatinine concentration. Consistently, there was a significant inverse linear dose-response relationship between baseline random urine creatinine and incident ESRD, but not all-cause mortality. Compared to patients with “medium” and “high-declining” urine creatinine trajectories combined, the adjusted hazard ratio for incidental ESRD among patients with a “stable-low” trajectory who had serial random urine creatinine concentrations stably below 100 mg/dL was 1.46 (95% CI: 1.00–2.12) after considering the competing risk of death. Conclusions Random urine creatinine not only serves as a common urinary concentration corrector but has its own clinical significance in risk stratification and outcome prediction in patients with advanced CKD.

Creatinine is a general marker as a screening test for renal disease. This study was conducted to provide basic data about pediatric concentration for serum and urine creatinine. The data from the 2011 Korean National Health and Nutrition Examination Survey was used. Analysis was done on 488 Children and Adolescents (boys 278, girls 210) aged 10 to 19, the Jaffe reaction method was used to gather the data. The highest serum creatinine levels were found in boys aged 19 to 20 years, the mean being 0.97 mg/dL (min 0.81 mg/dL, max 1.14 mg/dL). The levels showed increase over those in the 10 year old group. The highest urine creatinine levels were found aged 19 to 20 years, and the mean was 222.68 mg/dL (min 133 mg/dL, max 324 mg/dL). In the case of girls, the highest serum creatinine levels were found with those aged between 18 and 19, the mean being 0.71 mg/dL (min 0.49 mg/dL, max 0.84 mg/dL). The levels showed increase over the 11 to 18 year old group. The highest urine creatinine levels were found aged 14 to 15 years, and the mean was 218.44 mg/dL (min 131 mg/dL, max 321 mg/dL). The mean difference in serum creatinine in all age groups was statistically significant except for those aged 10 to 14, that of urine creatinine in all age groups was not significant statistically except for those aged 12 to 13, 17 to 18. Therefore, it is suggested that reference values for children and adolescents should be divided into different groups according to gender, further studies are needed using complementing data of the pediatrics.

Background. A creatinine clearance (CrCl) is still often requested to estimate the glomerular fi ltration rate (GFR) in clinical practice. However, the diversity of serum and urine creatinine (Scr, Ucr) assays leads to different CrCl-results which are here compared with each other and with the CKD-EPI eGFR-formula. Methods. We collected information on urine volume, Ucr and Scr using Roche ’ s enzymatic (E), compensated Jaffe (CJ) and Jaffe (J) assay for 589 patients. To allow comparison with the CKD-EPI prediction results, CrCl was normalized for body surface area. Results. Differences between CrCl-E and CrCl-CJ are rather small as opposed to the large differences with CrCl-J. However, two compensating errors in the CrCl-J calculation result in a closer agreement with CKD-EPI eGFR, than between CrCl-CJ or CrCl-E and CKD-EPI eGFR. The explained variance R 2 in all three cases is smaller than 0.66, demonstrating the very large scatter of the data around the regression line. Conclusions. CrCl determination is very assay-dependent. Although many clinical labs have switched to ID-GC/MS-standardized assays (E and CJ) for the determination of Scr and Ucr to improve analytical accuracy, the increased deviation of the normalized CrCl from the CKD-EPI prediction illustrates that the use of CrCl remains questionable for clinical practice. When a CrCl is requested, we would even recommend clinical labs who work with compensated Jaffe assays not to compensate the Scr-J value.

Introduction: Proteinuria is a common marker of kidney damage. This study aimed at determining predictors of proteinuria in subjects without impaired renal filtration function in Owerri, Nigeria. Methods: This was a cross-sectional study involving 136 subjects, consecutively drawn from Federal Medical Centre (FMC), Owerri, Nigeria. Relevant investigations were performed, including 24-hour urine protein (24HUP). Correlation and multivariate linear regression analysis were used to determine the association and strength of variables to predict proteinuria. Proteinuria was defined as 24HUP ≥0.300g and impaired renal filtration function as creatinine clearance (ClCr)

Background Urinary C-peptide creatinine ratio (UCPCR) is a non-invasive and convenient way of assessing endogenous insulin production. Adjusting for urine creatinine levels allows for differences in urine concentration. Creatinine excretion is known to be higher in men due to gender differences in muscle mass. We investigated the impact of gender on UCPCR. Methods One hundred and seventy-six subjects underwent a mixed meal tolerance test (MMTT). We looked at the relationship between UCPCR on urine C-peptide and creatinine excretion rates using timed post-meal urine samples. A further 415 subjects had two-hour post-meal UCPCR measurements in order to derive gender-specific percentiles for different diabetes subgroups and controls. Results UCPCR was 1.48-fold higher in women ( n= 78) than men ( n= 98), median (interquartile range [IQR]): 1.88 (0.49–3.49) men versus 2.88 (1.58–4.91) nmol mmol−1 women, P= 0.01. This reflects a gender difference in creatinine excretion rates (11.5 [8.3–13.7] men versus 8.2 [5.6–9.1] women μmol min−1 P < 0.001). C-peptide excretion rate was similar in men and women (19.8 [5.2–37.0] versus 22.1 [7.4–40.5] pmol min−1, P = 0.7). UCPCR was higher in women in all subgroups defined by diabetes classification and treatment, except long-term type 1 diabetes in whom C-peptide secretion was minimal. Conclusions Gender affects UCPCR, with higher values found in women. This results from lower urine creatinine reflecting gender differences in muscle mass. This necessitates gender-specific ranges for accurate interpretation of UCPCR results.

The aim of this study was to clarify the effect of aging on renal function. Serum creatinine (SCr), blood urea nitrogen (BUN) and 24-h creatinine clearance (measured-CrCl) were examined in lung cancer patients and the measured-CrCl were compared with CrCl estimates by employing two commonly used equations. In total, 787 lung cancer patients who were diagnosed between 2001 and 2010 were retrospectively analyzed. SCr and urine creatinine, BUN and measured-CrCl were evaluated prior to treatment. The Cockcroft-Gault (CG) and modification of diet in renal disease (MDRD) formulae were also used to estimate CrCl. SCr, BUN and measured-CrCl showed a significant decline in the elderly. In the 787 lung cancer patients, a significant correlation coefficient was found between measured-CrCl and age. However, in patients aged 80 years or older, no significant correlation coefficient was found between measured-CrCl and age. In the comparison between the measured CrCl and the CrCls estimated by the two formulae, the CG-CrCl levels were lower than those of the measured-CrCl, whereas the MDRD-CrCl levels were higher. Age is a crucial factor influencing renal function in patients with lung cancer. Particularly in the elderly, a decline in CrCl and greater individual variability in CrCl, as well as discrepancies in measured-CrCl and estimated CrCls are significant factors.

Technetium-99m diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) is an ideal radioisotopic method having a high correlation with inulin clearance for the determination of glomerular filtration rate (GFR). Different formulas like creatinine clearance (CrCl) in 24 h urine samples, Cockroft-Gault formula (CGF), and modification of diet in renal disease (MDRD) are being used to come up with an estimate. In this study, we compared (99m)Tc-DTPA with the formulas mentioned above in an attempt to best identify the method that would yield the nearly ideal GFR estimates in the elderly.In 76 patients who were admitted to our clinic, we measured 24 h urine volume (V), urine creatinine (Ucr), and serum creatinine (Scr) levels together with CrCl, Scr, serum urea (Su), and albumin (Alb) levels. By using coefficients identified for age, gender, and race, we calculated modification of diet in renal disease 1 (MDRD1). Different from MDRD1, we calculated modification of diet in renal disease 2 (MDRD2) that does not include Su and Alb parameters and formulas like CGF that include Scr, age, gender, and weight parameters to come up with GFR levels. All patients underwent (99m)Tc-DTPA procedure.The mean of the GFR values measured by (99m)Tc-DTPA was 54.3 ± 19.9. The means of GFR values calculated by CrCl, MDRD1, MDRD2, and CGF were 58.0 ± 30.5, 60.9 ± 22.1, 54.4 ± 20.1, and 57.9 ± 22.4, respectively. GFR as measured by (99m)Tc-DTPA showed statistically significant correlations with the results of other methods (p0.001 for all methods). The most significant correlation was with MDRD1.MDRD1 can be used for next to ideal and accurate predictions of GFR in the elderly in the daily practice.

Context.—Light chain disease represents 15% to 20% of cases of multiple myeloma. Current guidelines recommend monitoring these patients with 24-hour urine collections.Objective.—To determine the reliability of 24-hour urine collections in assessing the amount of Bence-Jones protein (BJP).Design.—We included all patients from our institution from 2003 through 2008 with BJP who had more than four 24-hour urine collections. We compared BJP excretion calculated from the submitted 24-hour collection with BJP excretion calculated by normalizing the collection to that patient's mean 24-hour creatinine excretion. We also looked at differences in serial values with these 2 methods. In addition, we evaluated the feasibility of using random urine samples to determine BJP excretion.Results.—A total of 14 patients with 135 24-hour urine collections met our inclusion criteria. The 24-hour urine creatinine excretion for each patient, which should be reasonably constant, varied considerably (coefficient of variation range 12%–30%). Differences in the 2 methods of calculating BJP excretion ranged from −1588 to 2315 mg/d. Among a total of 121 serial 24-hour measurements, the differences were clinically significant in 37 (30%). Among a total of 23 random urine samples from 11 of these patients submitted within 10 days of a 24-hour collection, the estimated BJP excretion appeared to be accurate in at least 18 (78%).Conclusions.—Twenty-four–hour urine collections for BJP are, in practice, often misleading. At a minimum, one should verify that the 24-hour creatinine excretion is accurate. In addition, it may be possible to use the protein/creatinine ratio from random urine samples to determine 24-hour BJP excretion.

Our study was developed to ascertain reference ranges of 11-dehydrothromboxane B2 (11-dhTXB2) in the urine of healthy pediatric subjects. Urine samples were analyzed using the AspirinWorks™ assay that measures levels of 11-dehydrothromboxane B2. 128 individuals (2 months to 18 years) were identified as healthy and not receiving aspirin. When adjusted as picograms/milligrams urine creatinine, there was a negative correlation between age and level of 11-dehydrothromboxane B2 (P = 0.0001). This study confirms a negative correlation between age and level of urinary 11-dehydrothromboxane B2 and provides a set of age-specific reference ranges. Pediatr Blood Cancer 2014;61:2074–2076. © 2014 Wiley Periodicals, Inc.

Context: Postexercise urine lactate may be a novel biomarker of lactate production capacity during exercise.Objective: To evaluate the reliability and utility of the urine lactate concentration after maximal swimming trials between different training protocols (6 × 50 m and 3 × 100 m) and training states (active and nonactive swimmers).Materials and methods: Lactate and creatinine were determined by spectrophotometry in blood and urine.Results: Blood and urine lactate concentrations were correlated in-between training protocols and in participants of different training states. The reliability of the urine lactate concentration was moderate for one of the training protocols and good or moderate for the two training states. Additionally, it was lower than that of the blood lactate concentration, and did not improve after normalizing to the urine creatinine concentration.Discussion and conclusion: Although promising as a biomarker of lactate production capacity, urine lactate requires further researc...

Background: Impaired kidney function can affect levels of urine (UCR) and serum creatinine (SCR). Objective: Data from National Health and Nutrition Examination Survey for the years 1999-2014 were used to study associations between UCR, SCR, and chronic kidney disease (CKD) stages 1-5. Results: Levels of SCR and UCR were positively correlated for CKD Stages 1-3 and negatively correlated for CKD Stages 4 and 5. Males had higher levels of UCR than females but male-female differences were narrower for CKD Stages 1-3 than for CKD Stages 4-5. Males had higher levels of SCR than females but male-female differences were 30% for CKD Stages 1-3 and 20% for CKD Stages 4-5. NHB had higher levels of UCR than NHW but these differences were 27.5 mg/dL for CKD Stages 1-3 and 17.9 mg/dL for CKD Stage 4 and 5. NHB had about 11% higher SCR levels than NHW for CKD Stages 1-3 and about 20% higher levels than NHW for CKD Stages 4-5. For CKD Stages 1-3, levels of UCR decreased with increase in CKD Stage but levels of SCR increased with increase in CKD Stage. Levels of both SCR and UCR were higher for CKD Sage 5 than for CKD Stage 4. Conclusions: CKD stages affect association between SCR and UCR as well as gender and racial/ethnic differences in both UCR and SCR.

Introduction Human immunodeficiency virus (HIV) infection is a global healthcare problem. Some diseases and physiological states may be altered in HIV-infected individuals. Our objective was to evaluate urine creatinine and factors that influence urine creatinine in treatment-naïve HIV subjects in Nigeria. Methods This was a cross-sectional study involving treatment-naïve HIV subjects in a tertiary hospital in Nigeria. Creatinine in spot and 24-hour urine samples and other relevant investigations were performed. Low urine creatinine or dilute urine was defined as 24-hour urine creatinine (24HUCr) 3000mg.Theassociation of low urine creatinine and high urine creatinine with potential risk factors was determined. Results The mean spot urine creatinine (SUCr) of the treatment-naïve HIV subjects was 137.21± 98.47(mg/dl), minimum value 13.3mg/dl, maximum value 533.3mg/dl and range of values 520.0mg/dl. The mean 24HUCr was 1507±781mg, minimum value 206mg, maximum value 4849mg and range of values 4643mg. Twenty four-hour urine creatinine3000mg in 24(6.4%) subjects. There was significant association between 24HUCr and serum low density lipoprotein cholesterol (LDL),serum high density lipoprotein cholesterol (HDL). There was high correlation between 24HUCr>3000mg and 24-hour urine osmolality (24HUOsm) (r=0.95), body mass index (BMI) (r=0.74), CD4 cells count (r=-0.71), serum HDL (r=-0.73). Conclusion The prevalence of dilute urine and concentrated urine was low. Twenty-four hour urine osmolality. BMI, CD4 cells count and HDL were strong correlates of high urine creatinine. Lipid abnormalities were common in treatment-naïve HIV subjects with high urine creatinine. There is need for clinicians to routinely conduct urine creatinine and further search for abnormalities of serum lipids, weight changes, depressed immunity and anemia in HIV subjects with dilute or concentrated urine in the early stages of the infection.

Bancha Satirapoj, Ketkan Jirawatsiwaporn, Theerasak Tangwonglert, Panbubpa ChoovichianDivision of Nephrology, Department of Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok, ThailandBackground: Glomerular filtration rate (GFR) is considered the indicator of overall kidney function, and therefore, its assessment has become an important clinical tool in the daily care of chronic glomerulonephritis (CGN) patients. Currently, practical guidelines recommend using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations to assess GFR in CKD patients.Methods: A cross-sectional study was performed in CGN patients. Standard GFR was measured using 24-hour urine creatinine clearance. GFR was estimated using the Cockcroft-Gault, Modification of Diet in Renal Disease, CKD-EPI equation based creatinine, cystatin C, and combined creatinine and cystatin C. The performance of GFR estimation equations were examined using bias, precision and accuracy and agreement between standard GFR and estimated GFR by calculating Cohen’s k.Results: A total of 125 patients (74 male, 59.2%) with mean age 56.1±18.1 years were included. Mean standard GFR was 51.6±32.2 mL/min per 1.73 m2. A significant correlation was found between standard GFR and all estimated GFRs (r=0.573 to 0.660, P

Adding to the complexity of caring for critically ill patients is the fact that many of them have a creatinine clearance that exceeds 130 mL/min/1.73 m2. This phenomenon, termed augmented renal clearance (ARC), has only recently been widely recognized and its pathogenesis remains incompletely understood. However, ARC has been shown to result in increased dose requirements for drugs that are primarily eliminated by renal excretion, including many antimicrobial agents and enoxaparin. Recognition of ARC is hampered by the fact that the standard creatinine-based equations used to estimate renal function are not accurate in this clinical setting and the diagnosis is best established using both serum and urine creatinine measurements to calculate clearance. So a high index of clinical suspicion and awareness is usually required before this step is taken to confirm the diagnosis of ARC.

The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines suggest that clinicians use the estimated glomerular filtration rate (eGFR) measurements and minimize the use of timed urine creatinine clearance collection. The intent of this change was to improve recognition of chronic kidney disease. Here we used time-series modeling and intervention analyses to determine the effect of publication of the K/DOQI guidelines and the introduction of widespread eGFR reporting with prompts on physician ordering of 24-h urine collection for creatinine clearance. In this setting, clinical practice guidelines did not influence creatinine clearance testing; however, the direct introduction of eGFR reporting with prompts into physician workflow resulted in a sudden and significant 23.5% decrease in creatinine clearance collection over the 43 months analyzed. Thus, eGFR reporting with prompts may have produced a clinical practice change because it is integrated directly into physician workflow. Changing physician practice patterns may require more than publishing guidelines; rather it is more likely to occur through educational and structural changes to practice.

Background: The albumin-to-creatinine ratio and the 24-hour urine collection to measure microalbuminuria are inconvenient and expensive. The newer rapid and less expensive dipstick methods for screening of microalbuminuria estimate only albumin and are subject to errors caused by variation in volume. We determined the relation between urine-specific gravity (Usg) and urine creatinine (Ucr) so that Ucr can be derived from Usg to correct for albumin concentration in the urine which is influenced by urine volume. Methods: We randomly included 42 consecutive patients from the primary care clinic, and 34 patients from the diabetic clinic. Results: We found that a very good correlation existed between Usg and Ucr in the 42 patients from the primary care clinic (Ucr = 11.4 × Usg –11,509, r = 0.83, p < 0.001). Patients from the diabetic clinic who had well-controlled blood sugar (n = 21) showed a similar trend (Ucr = 10.82 × Usg –10,882, r = 0.87, p < 0.001). However, this was not the case with uncontrolled diabetics (Ucr = 2.53 × Usg –2,513, r = 0.26, NS). Using simple arithmetic, we derived a simplified formula where Ucr can be predicted from Usg. Using multiple regression to incorporate the urinary glucose level by dipstick, a more generic formula was obtained for estimating urinary creatinine. Conclusion: Usg can be used instead of Ucr to normalize for the varied urine concentration while screening for microalbuminuria. Poorly controlled diabetics should be screened after their blood sugars are well controlled or use the more generic formula that incorporates urinary glucose. Thus, by measuring spot urine albumin and specific gravity by dipsticks one gets an easy, immediate and accurate estimation of microalbuminuria in an office setting.

A 57-year-old woman presented with swelling and thickening of the skin of the lower extremities. Three months prior to presentation, patient had MRI with gadolinium as part of an evaluation for suspected pancreatic malignancy. Creatinine levels at the time of gadolinium exposure were 0.9–1.2 mg/dL, with a corresponding estimated glomerular filtration rate of 64 mL/min/1.73m(2) by modification of diet in renal disease equation. Twenty-four-hour urine creatinine clearance was performed as an outpatient following development of symptoms. This revealed a creatinine clearance of 23 mL/min, suggestive of advanced chronic kidney disease despite an estimated glomerular filtration rate of 64 mL/min/1.73m(2). Skin biopsy was positive for sclerosing dermopathy. These findings, in addition to the temporal association with gadolinium exposure, led to the diagnosis of nephrogenic systemic fibrosis.

Graft survival after pancreas transplantation alone (PTA) is significantly poorer than graft survival after simultaneous pancreas kidney (SPK) and is particularly affected by difficulty in monitoring rejection. Exocrine bladder drainage allows assessment of pancreas graft function as urinary amylase (UA). However, standards for UA collection and interpretation are not well defined. In this study, 21 bladder-drained PTA recipients were monitored with daily values for UA and urine creatinine (Creat) concentration from post-transplant 10-mL samples and 24-h collections. Clinical events were documented and correlated to UA measurements. UA values were found to increase post-transplant until day 15, and large interpatient variability was noted (median 12 676 IU/L, range 668-60 369 IU/L). A strong correlation was found total 24-h UA production and spot UA/Creat ratio (r = 0.80, p 0.001). UA/Creat ratio showed less variation during episodes of impaired renal function; therefore, urinary amylase baseline was defined as the median UA/Creat ratio after day 15. A 25% decrease of UA predicted 9/13 (69%) events. We conclude that individual baselines should be set once the values have stabilized after 15 d post-transplant and that spot UA/Creat measures are reliable, patient friendly and indicate potential events after PTA.

Purpose: Carboplatin is frequently dosed to achieve a desired area under the plasma concentration-time curve (AUC) by using the Calvert or Chatelut equations to estimate carboplatin clearance. Accurate determination of glomerular filtration rate (GFR) is necessary to correctly calculate carboplatin clearance using the Calvert equation. In clinical practice, the Cockcroft-Gault formula is frequently used to estimate GFR, but this practice has been reported to under- and overestimate carboplatin clearance. The purpose of this trial was to compare determinations of carboplatin clearance using the Chatelut equation and four separate GFR determinations, including 99mTc-DTPA, the Cockcroft-Gault formula, a 24-h urine collection and a 2-h urine collection. Methods: Carboplatin clearance was estimated in 21 previously untreated extensive-stage small-cell lung cancer patients. GFR was determined using 99mTc-DTPA, the Cockcroft-Gault formula, 24-h urine collection and 2-h urine collection. Serum and urine creatinine concentrations were measured using enzymatic assays. The carboplatin clearance was then calculated by individually adding 25 to the four GFR determinations based on the Calvert equation, which states that carboplatin clearance equals GFR+25 (nonrenal clearance). The carboplatin clearance was also estimated using the Chatelut equation. The five determinations of carboplatin clearance were compared using Friedman's test and post-hoc Wilcoxon signed rank tests. Precision and bias for each carboplatin clearance determination were calculated assuming that 99mTc-DTPA provided the most accurate measure of GFR. Results: A statistically significant difference was found between the five methods of estimating carboplatin clearance (P

Substantial research has focused on the discovery of urinary biomarkers to detect acute kidney injury (AKI) before a rise in serum creatinine. As in chronic kidney diseases, the concentrations of urinary AKI biomarkers have been normalized to urine creatinine concentration to account for creatinine clearance and urine flow. Waikar et al. challenge the assumption that normalization to creatinine clearance in a chronic disease state can be extrapolated to an acute state, in which creatinine clearance is, by definition, changing acutely.

The measurement of urinary creatinine is important in many situations, but perhaps most important when measuring the urinary content of substances other than creatinine. Because urine flow changes unpredictably during the day, but total creatinine output is generally constant, many investigators normalize their results to creatinine content (i.e. mg chromium/mg creatinine). Because the widespread use of creatinine levels make the reliability of their measurement important, we decided to test this by studying the effects of storage time and temperature on urine specimens obtained from 10 healthy adults. Our results showed that only prolonged storage time at high temperatures (30 days, 55 degrees C) could cause significant decreases in urine creatinine levels. When stored for 2 days at 55 degrees C the decrease in urine creatinine levels was < 3%. We conclude that in all but extreme cases urine creatinine is virtually unaffected by storage time and temperature.

Background: Creatinine clearance is safest method to measure glomerular filtration rate (GFR) in pregnancy. The objectives was to study a case-control study conducted in Omdurman Maternity Hospital aimed to assess GFR, using creatinine clearance and magnitude of changes of serum creatinine in pre-eclampsia.Methods: Pre-eclamptic were 70, normal pregnant 96 and non-pregnant 63. Investigations were done at St Hellier's hospital London. Serum and urine creatinine were measured using Jaffé reaction and spectrophotometer. 24-hour urine output was measured and creatinine clearance calculated to find GFR. GFR was calculated in ml/min/mm2 using John Hopkins’ method.Results: The mean serum creatinine in pre-eclamptic (68.6µmol/L) was less than non-pregnant (75.5µmol/L) (P=0.001) but was higher than normal pregnant (62.4µmol/L) (P=0.003). Mean GFR pre-eclamptic (68.6ml/min.1.73m2) was less than non-pregnant (87.0ml/min/1.73m2) (P=0.0001) and normal pregnant (89.0ml/min/1.73ml/min/1.73m2) (P =0.0001).Conclusions: GFR decreased at term in normal pregnancy and even more in pre-eclampsia. Serum creatinine levels increased and did not correlate with GFR changes in pre-eclampsia.

Age-adjusted reference ranges for creatinine clearance were determined in 279 women, ages 40-95 years, who were housed in a metabolic research unit and consumed a meat-free diet. Creatinine clearance, but not serum creatinine, declined with age by 0.63 mL/min per 1.73 m2 per year. Serum and urine creatinine concentrations, used to calculate clearances, were analyzed by a kinetic Jaffé procedure. In a subset of 100 subjects, fasting serum creatinine values averaged 8.3 +/- 5.2 (SD) mumol/L higher when measured by the kinetic Jaffé procedure than by an enzymatic method (creatinine PAP). The Cockcroft-Gault formula for estimating creatinine clearance from serum creatinine in women was validated, and the modification factor for the male equation was determined to be 0.84 (95% confidence interval 0.83-0.86) confirming the suggested 15% correction. A prediction formula derived from this population was similar in accuracy to the Cockcroft-Gault formula.

To determine the possibility of plasma citrate as a biomarker in patients with glaucoma.Twenty-one consecutive Caucasian patients with glaucoma and 21 sex- and age-matched controls were investigated. Plasma citrate, plasma creatinine, urine citrate, and urine creatinine were analyzed by ion chromatography. Mean (±standard deviation) concentrations and the calculated fractional citrate excretions were compared using the Mann-Whitney test. Sensitivity and specificity to detect glaucoma using plasma citrate levels were calculated.The mean plasma citrate (104.8±23.2 vs. 128.2±31.1 μmol/L; P=0.01) concentrations were significantly lower among the patients with glaucoma, whereas the mean urine citrate concentrations (1.7±0.9 vs. 2.8±1.9 μmol/L; P=0.07) were slightly lower. Mean plasma and mean urine creatinine concentrations showed no significant differences (plasma creatinine: 63.0±16.7 vs. 63.4±15.5 μmol/L; P=0.72; urine creatinine: 9.6±5.1 vs. 11.5±8.4 μmol/L; P=0.67). The calculated fractional citrate excretions were also not different with 12.1% versus 13.6% (P=0.37). Setting the cut-off limit at 110 μmol/L, the plasma citrate level evaluation would have a sensitivity of 66.7% and a specificity of 71.4% to detect glaucoma.In this masked study, plasma citrate levels were significantly decreased in Caucasian patients with glaucoma giving the possibility to use them eventually as a biomarker. The kidney function was normal in both groups, leaving the etiology of this hypocitraemia yet unexplained.

Polyuria and polydipsia, common symptoms in psychiatric patients, cause significant morbidity. No convenient and reliable method exists to diagnose, or determine the severity, of these disorders in water balance (Vieweg and Leadbetter 1990). Accurate measures of intake or output are difficult to obtain (Vieweg and David 1985); estimates based on patient or staff reports are unreliable (lllowsky and Kirch 1988); and changes in body weight or serum sodium are insensitive. Many rely on spot measures of urine dilution (Vieweg et al 1986), though these methods have only been validated in a single abstract (Koczapski et al 1989). These author's found that early morning and late afternoon urine creatinine concentrations in male polydipsic inpatient chronic schizophrenics, adjusted for body weight, are highly correlated to measured 24hr urine volumes. The goals of this study were to test Koczapski and colleagues' method in polydipsic and nonpolydipsic subjects, and to examine the influence of other putative factors on the relationship between urine creatinine concentration and measured 24-hr urine output. We also calculated

Objectives: To assess the effects of severity of renal failure on kidney size. Subjects and Method: Ninety adult subjects [56 male 34 female] were recruited from the renal clinic of University of Nigeria Teaching Hospital, Enugu, over a period of 13 consecutive months. History and physical examination were carried out on initial visit. Their GFR was determined by urine creatinine clearance. The subjects were grouped into 3 – Group 1 GFR 11 – 20mls/min, Group 2 GFR 6 – 10mls/min, Group 3 GFR ≤5mls/min. Their kidney sizes were measured using ultrasonography. Results In both male and female subjects, mean kidney size reduced progressively as GFR deteriorated. Mean kidney size in male subjects in group 1 was 9.2cm±0.2. Group 2 was 8.4cm±0.5, Group 3 was 7.9cm±0.5. Mean kidney size in female subjects was as follows – Group 1-8.9cm±0.1, Group 2 – 8.2cm±0.1, Group 3 -8.0cm±0.5. Conclusion Mean kidney sizes were reduced as GFR worsened progressively Keywords : Ultrasonography, Kidney sizes, Enugu, Nigeria Tropical Journal of Medical Research Vol. 12 (1) 2008: pp. 6-8

The excretion of urinary protein was evaluated in 62 owl monkeys using timed urine collections. The ratio of urine protein to urine creatinine concentrations (Up/c) was determined for each monkey. Linear regression analysis was used to calculate the correlation between that ratio and urine protein (mg/dl) and 24-hour urinary protein loss (mg/kg). The coefficient of determination for Up/c to urine protein and 24-hour urinary protein loss was significant (P less than or equal to 0.0001). Determination of the Up/c in a urine specimen was found to be an acceptable diagnostic technique for detection and quantitative estimation of proteinuria.

The accurate measurement of low serum creatinine levels is necessary for estimating clinically useful creatinine clearances in the pediatric population. This study compares two routine clinical methods: the kinetic Jaffé with the newer Kodak enzymatic method against our reference method, high-pressure liquid chromatography, for the measurement of serum and urine creatinine levels in neonates. One hundred and twenty-five serum and 59 urine creatinines and 56 absolute creatinine clearances were measured in neonates ranging from 23 to 46 weeks (mean 32 weeks) post-conceptional age and weighing 480-4398 g (mean 1650 g). Urine creatinine levels, and serum creatinine levels greater than 0.8 mg/dl were equivalent for both clinical methods. However, the enzymatic method was much more accurate (P less than 0.001) than the kinetic Jaffé method for serum creatinine measurements of less than or equal to 0.8 mg/dl. We conclude that the enzymatic methodology is a better clinical choice for the accurate measurement of serum creatinine levels when using these values for the determination of neonatal renal function.

Some diseases, environmental pollutants and physiologic states may influence urine creatinine. Urine creatinine is not routinely evaluated in the general out-patient population. The objective of this study was to evaluate urine creatinine and factors that may influence it in subjects attending the general out-patient clinic in a tertiary hospital in Nigeria. This was a cross-sectional study involving subjects consecutively recruited from a general out-patient clinic in Federal Medical Centre, Owerri, Nigeria. Creatinine in spot and 24-hour urine samples and other relevant investigations were performed. Dilute urine or low urine creatinine was defined as 24-hour urine creatinine (24HUCr) 3000mg.The association of variables with urine creatinine and the strength of variables to predict dilute and concentrated urine were determined. The mean spot urine creatinine (SUCr) of the subjects was 148±167mg/dl, minimum value 14.7mg/dl, maximum value 746.7mg/dl and range of values 732.0mg/dl. The mean 24HUCr was 1203±316mg, minimum value 651.0mg, maximum value 2320mg, and range of values 1669.0mg. All the subjects have 2HUCr in the normal range. Spot urine creatinine has significant correlation with body mass index, spot urine protein (SUP), spot urine osmolality, 24-hour urine protein (24HUP), 24HUCr, serum creatinine, serum cholesterol and serum low density lipoprotein cholesterol. In contrast, 24HUCr has significant correlation with 24-hour urine volume, serum creatinine and serum cholesterol. Spot urine protein and 24HUP predicted SUCr, while only serum creatinine predicted 24HUCr. Low and high urine creatinine were absent in subjects attending the general out-patient clinic. Proteinuric renal abnormalities were common in these subjects with normal urine creatinine. There is need for clinicians to routinely conduct urine creatinine and further search for renal damage, dyslipidemia and abnormal weight changes in the general out patients with normal urine creatinine.