Quantification of proteinuria in children using the urinary protein-osmolality ratio

Kim, Hyun Soo; Cheon, Hae Won; Choe, Jeong-Hoon; Yoo, Kee Hwan; Hong, Young Sook; Lee, Joo Won; Kim, Soon Kyum

doi:10.1007/s004670000486

Cited by 23 publications

(14 citation statements)

References 18 publications

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“…The performance and validity of urine osmolality adjustment in environmental biomonitoring has not been evaluated, although a few studies have supported that albumin-to-osmolality ratio or protein-to-osmolality ratio correlates closely with 24-hour measurements (Gyamlani et al, 2003; Kim et al, 2001; Morgenstern et al, 2003). In our study, we found that the variation in urine osmolality related to socio-demographic background and medical conditions was less dramatic compared to urine creatinine.…”

Section: Discussionmentioning

confidence: 99%

Urine osmolality in the US population: Implications for environmental biomonitoring

Yeh¹,

Lin²,

Kuo³

et al. 2015

Environmental Research

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Background For many environmental chemicals, concentrations in spot urine samples are considered valid surrogates of exposure and internal dose. To correct for urine dilution, spot urine concentrations are commonly adjusted for urinary creatinine. There are, however, several concerns about the use of urine creatinine. While urine osmolality is an attractive alternative; its characteristics and determinants in the general population remain unknown. Our objective was to describe the determinants of urine osmolality and to contrast the difference between osmolality and creatinine in urine. Methods From the National Health and Nutrition Examination Survey (NHANES) 2009–2012, 10,769 participants aged 16 years or older with measured urine osmolality and creatinine were used in the analysis. Very dilute and very concentrated urine was defined as urine creatinine lower than 0.3 g/l and higher than 3 g/l, respectively. Linear and logistic regression analyses were performed to investigate the associations of interest. Results Urine osmolality and creatinine were highly correlated (Pearson correlation coefficient = 0.75) and their respective median values were 648 mOsm/kg and 1.07 g/l. The prevalence of very dilute and very concentrated urine samples was 8.1% and 3.1%, respectively. Factors associated in the same direction with both urine osmolality and urine creatinine included age, sex, race, body mass index (BMI), hypertension, water intake, and blood osmolality. The magnitude of associations expressed as percent change was significantly stronger with creatinine than osmolality. Compared to urine creatinine, urine osmolality did not vary by diabetes status but was affected by daily total protein intake. Participants with chronic kidney disease (CKD) had significantly higher urine creatinine concentrations but lower urine osmolality. Both very dilute and concentrated urine were associated with a diverse array of sociodemographic, medical conditions, and dietary factors. For instance, females were approximately 3.3 times more likely to have urine over-dilution than male [the adjusted odds ratios (95% CI) = 3.27 (2.10–5.10)]. Conclusion Although the determinants of urine osmolality were generally similar to those of urine creatinine, the relative influence of socio-demographic and medical conditions was less on urine osmolality than on urine creatinine. Protocols for spot urine sample collection could recommend avoiding excessive and insufficient water intake before urine sampling to improve urine adequacy. The feasibility of adopting urine osmolality adjustment and water intake recommendations before providing spot urine samples for environmental biomonitoring merits further investigation.

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Section: Discussionmentioning

confidence: 99%

Urine osmolality in the US population: Implications for environmental biomonitoring

Yeh¹,

Lin²,

Kuo³

et al. 2015

Environmental Research

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“…Collecting these specimens accurately is difficult and time consuming, especially in infants and in patients suffering from incontinency or enuresis. Ratios of protein to osmolality 5 , 6 and protein to creatinine in single-voided urine specimens have been offered as appropriate tools for assessing urinary protein. 4 , 7 , 8 , 9 Urinary excretion of creatinine may vary in newborns 10 and spot urine may be influenced by the hydration-dehydration condition of patients.…”

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confidence: 99%

Quantification of proteinuria with urinary protein to osmolality ratios in children with and without renal insufficiency

Hooman¹,

Otoukesh²,

Safaii³

et al. 2005

Annals of Saudi Medicine

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BACKGROUNDSpot urine is recommended as an accurate method to determine proteinuria in children and adults. However, urinary excretion of creatinine may vary in newborns and spot urine may be influenced by the hydration-dehydration condition of patients. The study was done to assess the validity of the urine protein to osmolality ratio versus the urine protein to creatinine ratio in health and disease conditions.METHODSWe studied the correlation of the urine protein-osmolality ratio (Uprot/Uosm) and the urine protein to creatinine ratio (Up/Ucr) and compared results with the 24-hour urinary protein excretion. Three groups were compared: children with normal renal function and without proteinuria (group 1, n=53), children with normal renal function and with proteinuria (group 2, n=52) and patients with renal insufficiency (group 3, n=45). Early morning urine samples and 24-hour urine specimens were collected for protein, creatinine, and osmolality.RESULTSThe optimal cutoff value of the Uprot/Uosm ratio was determined to be 0.33 mg/L/mosm/kgH2O for abnormal proteinuria and 1.75 mg/L/mosm/kgH2O for nephrotic range proteinuria. In comparing ROC curves, we found no differences between the Uprot/Uosm and Up/Ucr ratios in detecting abnormal proteinuria or nephrotic syndrome in children with normal or decreased renal function (P>0.05).CONCLUSIONBoth the Uprot/Uosm and Up/Ucr ratios from random urine specimens are good predictors of 24-hour urinary total protein excretion in children with and without renal insufficiency.

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“…Wilson et al reported in an adult study that the ratio of 0.12 of Uprot/Uosm was coincident with proteinuria with sensitivity 96% and specificity 93% by ROC curve method [8]. The cut-off value of Uprot/ Uosm ratio was 2.5 mg/l/mOsm/kg for estimating nephrotic proteinuria ([3 g/days) and correlation coefficient between Uprot/Uosm ratio and 24-h protein excretion was 0.88 in this study.…”

Section: Discussionmentioning

confidence: 82%

Protein–osmolality ratio for quantification of proteinuria in children

Serdaroğlu

Mır

2008

Clin Exp Nephrol

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Proteinuria is an important factor for renal injury and prognosis in many diseases. The most valuable method for evaluation of proteinuria is quantitative protein analysis in appropriately 24-h collected urine. But urine collection is difficult and cumbersome especially in children and working adults. The aim of the present study is to define the usefulness of urinary protein/urine osmolality (Uprot/Uosm) ratio in quantification of proteinuria. One hundred and seventy-one patients whose age ranged between 3 and 14 years were included in the study. Uprot/Uosm (r = 0.85, P < 0.001) and urinary protein/creatinine Uprot/Ucrea (r = 0.81 and P < 0.001) ratios were significantly correlated with 24-h protein excretion. Twenty-four-hour protein excretion was correlated with Uprot/Ucrea (r = 0.76, P < 0.001) and Uprot/Uosm (r = 0.79, P < 0.001) ratios in proteinuric group. But, there was no correlation between Uprot/Uosm and Uprot/Ucrea ratios with 24-h protein excretion in non-proteinuric group. The positive and negative predictive value of Uprot/Uosm ratio of 0.28 mg/l/mOsm/kg was 89.9 and 90.8% and Uprot/Ucrea ratio of 0.24 mg/mg was 85.7 and 90% for estimating proteinuria (above 4 mg/m2 h(-1)). The 95th percentile of Uprot/Uosm ratio was 0.25 mg/l/mOsm/kg and Uprot/Ucrea ratio was 0.27 mg/mg in normal group. The best estimate was Uprot/Uosm ratio of 1.42 (sensitivity 100%, specificity 94.9%) and Uprot/Ucrea ratio of 0.75 (sensitivity 100%, specificity 92.9%) for nephrotic proteinuria (40 mg/m2 h(-1)). Uprot/Uosm which is a reliable and simple method can be used for quantification of proteinuria in pediatric patients with normal renal function. Using Uprot/Uosm ratio for quantification of proteinuria can remove the necessity of 24-h urine collection, urine creatinine measurement and spending additional cost and time if the center measures the urine osmolality routinely in urine analysis.

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Quantification of proteinuria in children using the urinary protein-osmolality ratio

Cited by 23 publications

References 18 publications

Urine osmolality in the US population: Implications for environmental biomonitoring

Urine osmolality in the US population: Implications for environmental biomonitoring

Quantification of proteinuria with urinary protein to osmolality ratios in children with and without renal insufficiency

Protein–osmolality ratio for quantification of proteinuria in children

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