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Pediatric reference intervals for random urine calcium, phosphorus and total protein

Patricia R Slev1, Ashley M Bunker, William E Owen

  • 1ARUP Institute for Clinical & Experimental Pathology, Salt Lake City, UT, USA. patricia.slev@aruplab.com

Pediatric Nephrology (Berlin, Germany)
|May 18, 2010
PubMed

Insights

This study established age-specific urine reference intervals for calcium, phosphorus, and total protein in children and adolescents. These new pediatric reference ranges are crucial for accurate clinical interpretation.

Area of Science:

  • Clinical Chemistry
  • Pediatric Nephrology
  • Biomarker Research

Background:

  • Establishing accurate reference intervals for urinary analytes is essential for diagnosing and monitoring pediatric kidney function and metabolic disorders.
  • Existing reference ranges for calcium, phosphorus, and total protein in urine may not adequately reflect physiological changes during childhood and adolescence.
  • Age- and gender-specific reference values are critical due to developmental variations in renal function and solute excretion.

Purpose of the Study:

  • To determine age-appropriate reference intervals for urinary calcium (Ca), phosphorus (P), and total protein (UTP) in a pediatric population.
  • To establish reference ranges normalized to creatinine (Cr) to account for urine dilution variations.
  • To provide gender- and age-stratified reference intervals for improved clinical utility in children aged 7 to 17 years.

Main Methods:

  • Analyzed random urine samples from 674 boys and 728 girls aged 7–17 years.
  • Measured urinary Ca, P, and UTP using the Roche MODULAR P analyzer, with results normalized to urinary creatinine (Cr).
  • Employed non-parametric analysis to determine central 95% reference intervals with 90% confidence intervals, partitioned by gender and 2-year age groups.

Main Results:

  • Established distinct upper reference limits for Ca/Cr, P/Cr, and UTP/Cr, varying significantly with age and gender.
  • Observed a general trend of decreasing upper reference limits for all analytes as age increased.
  • Age was identified as a statistically significant factor influencing all measured urinary analytes, necessitating age-specific intervals.

Conclusions:

  • Proposed eight unique age- and gender-specific reference intervals for urinary Ca/Cr, P/Cr, and UTP in pediatric populations.
  • These findings provide crucial updated reference data for the accurate assessment of mineral and protein excretion in children and adolescents.
  • The established intervals will aid clinicians in the precise interpretation of urine tests for pediatric kidney and metabolic health.

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