Dataset Information

Relationship between Urine Creatinine and Urine Osmolality in Spot Samples among Men and Women in the Danish Diet Cancer and Health Cohort.

ABSTRACT: Assays of urine biomarkers often use urine creatinine to account for urinary dilution, even though creatinine levels are influenced by underlying physiology and muscle catabolism. Urine osmolality-a measure of dissolved particles including ions, glucose, and urea-is thought to provide a more robust marker of urinary dilution but is seldom measured. The relationship between urine osmolality and creatinine is not well understood. We calculated correlation coefficients between urine creatinine and osmolality among 1375 members of a subcohort of the Danish Diet, Cancer, and Health Cohort, and within different subgroups. We used linear regression to relate creatinine with osmolality, and a lasso selection procedure to identify other variables that explain remaining variability in osmolality. Spearman correlation between urine creatinine and osmolality was strong overall (ρ = 0.90; 95% CI: 0.89-0.91) and in most subgroups. Linear regression showed that urine creatinine explained 60% of the variability in urine osmolality, with another 9% explained by urine thallium (Tl), cesium (Cs), and strontium (Sr). Urinary creatinine and osmolality are strongly correlated, although urine Tl, Cs, and Sr might help supplement urine creatinine for purposes of urine dilution adjustment when osmolality is not available.

SUBMITTER: Ozdemir S

PROVIDER: S-EPMC8625939 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Relationship between Urine Creatinine and Urine Osmolality in Spot Samples among Men and Women in the Danish Diet Cancer and Health Cohort.

Ozdemir Selinay S Sears Clara G CG Harrington James M JM Poulsen Aslak Harbo AH Buckley Jessie J Howe Chanelle J CJ James Katherine A KA Tjonneland Anne A Wellenius Gregory A GA Raaschou-Nielsen Ole O Meliker Jaymie J

Toxics 20211101 11

Assays of urine biomarkers often use urine creatinine to account for urinary dilution, even though creatinine levels are influenced by underlying physiology and muscle catabolism. Urine osmolality-a measure of dissolved particles including ions, glucose, and urea-is thought to provide a more robust marker of urinary dilution but is seldom measured. The relationship between urine osmolality and creatinine is not well understood. We calculated correlation coefficients between urine creatinine and ...[more]

PMID: 34822673

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Project description:Rationale & objectiveArginine vasopressin (AVP) is an established driver of cyst growth in autosomal dominant polycystic kidney disease (ADPKD). Urine osmolality (osm) measures are surrogate markers of AVP activity. Both 24-hour and spot urine samples are used as indicators of AVP suppression. The agreement between these 2 measurements remains unclear.Study designA retrospective cohort study.Setting & study populationThree hundred and forty-nine patients with ADPKD with 839 urine samples from a tertiary care center.Selection criteria for studyPatients with ADPKD with records of spot and 24-hour urine measurements.Data extractionConsecutive patients' data from January 2018 to March 2023 were extracted from the quality assurance database of The Ottawa Hospital Cystic Kidney Disease Clinic.Analytical approachDiscordance assessed at target urine osmolality of 250 and 270 mmol/kg. Agreement assessed by Bland-Altman plots. The percentage of patients with difference in osmolality between the 2 measures for cutoff points of > 50, > 100, >150, and > 200 mmol/kg was calculated.ResultsThe mean 24-hour urine osm was 364 mmol/kg, and the mean spot urine osm was 424 mosm/kg. Mean age of 46 years, 52% females, and 47 (13.5%) were on tolvaptan. Overall, in comparing spot urine osm to 24-hour urine osm, the discordance at 250 and 270 mmol/kg was 24% with poor agreement on Bland-Altman plots. The differences between the 2 measures at varying cutoff points were 53.9% at 50 mmol/kg, 35.8% at 100 mmol/kg, 24.1% at 150 mmol/kg, and 16.1% at 200 mmol/kg. Results were similar when only a single measurement from each patient was used for analysis.LimitationsTotal of 29% of patients did not have concurrent spot urine osmolality and 24-hour urine osmolality. The study was conducted at a single center. Limited number of patients were on tolvaptan.ConclusionsIn adults with ADPKD, important differences exist between the 24-hour urine osmolality and spot urine osmolality that preclude interchangeable use. The method employed may impact clinical decision-making. More research is needed to determine, which urine osm should be used when assessing AVP suppression.

Project description:Metals in single spot urine samples are often used to estimate individual exposure in human studies. However, measurements in urine could vary greatly over time due to variable exposure, potentially leading to exposure misclassification.We examined the variability of metal levels in the urine of 11 men who provided 529 samples on 8 days during a 3-month period, which corresponds to the duration of spermatogenesis.The urinary levels of arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), lead (Pb), molybdenum (Mo), and nickel (Ni) were measured using inductively coupled plasma-mass spectrometry. We calculated the intraclass correlation coefficients (ICCs) to assess the reproducibility of metal measures and computed the sensitivity and specificity to evaluate how well spot urine samples determined the individuals' 3-month average exposure.Fair to good reproducibility was observed for the serial measurements of Cd (ICC = 0.53) in spot samples collected during the 3-month period, whereas the serial measurements of As, Co, Cu, Pb, Mo, and Ni showed poor reproducibility (ICCs = 0.01-0.29). Use of single spot urine samples to classify the high (top 33%) 3-month average metal levels had uniformly high specificities (0.70-0.84) but relatively low sensitivities (0.40-0.57), except for Cd (0.77). The minimum number of specimens (k) required to estimate the participant-specific mean for the seven metals within 20% of the "true" values ranged from 3 for Cd to 27 for Ni.The high variability observed in the urinary levels of As, Co, Cu, Pb, Mo, and Ni suggests that a single measurement provides only a brief snapshot in time of the exposure levels of an individual, which can result in a moderate degree of exposure misclassification.Wang YX, Feng W, Zeng Q, Sun Y, Wang P, You L, Yang P, Huang Z, Yu SL, Lu WQ. 2016. Variability of metal levels in spot, first morning, and 24-hour urine samples over a 3-month period in healthy adult Chinese men. Environ Health Perspect 124:468-476;?http://dx.doi.org/10.1289/ehp.1409551.

Dataset Information

Relationship between Urine Creatinine and Urine Osmolality in Spot Samples among Men and Women in the Danish Diet Cancer and Health Cohort.

Publications

Relationship between Urine Creatinine and Urine Osmolality in Spot Samples among Men and Women in the Danish Diet Cancer and Health Cohort.

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