Reference Intervals of Spot Urine Creatinine-to-Osmolality Ratio as a Surrogate of Urinary Creatinine Excretion Rate

• Published in: Disease markers Vol. 2022; pp. 1 - 11
• Main Authors: Hsu, Shih-Ping, Chien, Chiang-Ting
• Format: Journal Article
• Language: English
• Published: Amsterdam Hindawi 25.07.2022; John Wiley & Sons, Inc
• Subjects: Adults; Antihypertensives; Biochemistry; Blood pressure; Body weight; Collaboration; Creatinine; Customization; Demographics; Diabetes; Diuretics; Enzymes; Excretion; Human subjects; Hypertension; Intervals; Laboratories; Minority & ethnic groups; Nutrition; Regression analysis; Self report; Urea; Urine; Variance analysis; United States > US
• ISSN: 0278-0240; 1875-8630; 1875-8630
• DOI: 10.1155/2022/3549047

A spot urine creatinine-to-osmolality ratio (sUCr/Osm) is proposed as a surrogate of the urinary excretion rate of creatinine (Cr) and convenient for forecasting serum Cr (SCr) trends. The lower the sUCr/Osm, the lower the excreted Cr amount accompanied by per unit of osmoles, the higher the risk of Cr accumulation. For exploring the reference intervals of sUCr/Osm in general adults, a cross-sectional analysis was performed on a subset of data from the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Of the eligible 3,316 adults aged 18.0 to 79.9 years, the age (mean±SD) was 45.2±17.2 years old, women was 45.02%, body weight (BW) was 76.1±14.5 kg, and African Americans was 23.6%. Blood urea nitrogen (BUN) was 12.6±4.7 mg/dL; SCr was 0.89±0.34 mg/dL. As spot urine Cr and osmolality were 127.1±84.0 mg/dl and 649±266 mOsm/kg, respectively, sUCr/Osm was 0.19±0.08. With adjustment of factors related to personal urinary excretion of Cr and osmoles by multivariable regression analysis, the estimated sUCr/Osm (esUCr/Osm) for an individual was 0.153×age in year−0.070×BW in kg0.283×1.244 if African American×BUN in mg/dL−0.310×SCr in mg/dL0.681. The index of sUCr/Osm to personalized esUCr/Osm was 1.05±0.39. When only low urinary excretion of Cr is likely to be of clinical concern, further analysis showed 157 individuals (4.7%, outside the 5th percentile) had their original sUCr/Osm<0.08; 157 had the sUCr/Osm indexed for personalized esUCr/Osm<0.50.