Reference intervals for 24 laboratory parameters determined in 24-hour urine collections

Area of Science:

• Clinical Chemistry
• Biomarker Discovery
• Urine Analysis

Background:

• Existing reference intervals for 24-hour urine tests are often unavailable, lack sex specificity, or are based on small, non-representative samples.
• This limits their utility in accurate clinical diagnosis and population health assessment.

Purpose of the Study:

• To establish comprehensive, sex-specific reference intervals for a wide range of laboratory parameters in 24-hour urine collections.
• To provide updated reference values based on a large, population-based cohort of asymptomatic adults.

Main Methods:

• Analyzed 24-hour urine samples from 241 adults (121 men, 120 women) for 24 parameters, including electrolytes, metabolites, and proteins.
• Calculated creatinine-normalized ratios for 16 parameters and determined reference intervals using CLSI C28-A3 guidelines.

Main Results:

• Significant sex-specific differences were observed for 12 of 24 urine parameters and 8 of 16 creatinine-normalized ratios.
• Reference intervals for six urine excretion and four ratio parameters were established for the first time.
• Notable deviations from previous intervals were found, particularly for 24-hour urine cortisol in women.

Conclusions:

• This study provides the most extensive set of sex-specific reference intervals for 24-hour urine parameters to date.
• Utilizing modern analytical methods and a large cohort ensures reliable reference values aligned with CLSI guidelines.
• These findings enhance the accuracy of laboratory diagnostics for a broad spectrum of clinical conditions.