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Evidence for systematic temporal variation in 24-hour urinary creatinine excretion
Journal of Clinical Pharmacology
|February 1, 1977
Summary
Urinary creatinine levels in healthy males show significant biological and temporal variations, with a distinct annual oscillation. These findings highlight the need to account for individual and seasonal factors in creatinine analysis.
Area of Science:
- Clinical Chemistry
- Human Physiology
- Biostatistics
Background:
- 24-hour urinary creatinine excretion exhibits considerable variability.
- Understanding factors contributing to this variability is crucial for accurate clinical interpretation.
Purpose of the Study:
- To analyze factors contributing to the large standard deviation and range in 24-hour urinary creatinine specimens.
- To identify sources of error in creatinine measurements.
Main Methods:
- Analysis of 557 24-hour urinary creatinine specimens from eight healthy males over 6-10 months.
- Statistical analysis of within- and between-subject variations, including temporal dependencies.
Main Results:
- Subject means correlated significantly with weight and surface area.
- Between-sequence differences exceeded within-sequence differences.
- A biphasic function, approximately 12 months long, described pooled data with seasonal peaks and troughs.
- Estimated error sources: measurement +/- 3%, biological +/- 6%, mixed biologic-temporal +/- 6%, random +/- 5%.
Conclusions:
- Individual biological variations, time dependencies, and seasonal patterns significantly influence urinary creatinine levels.
- Accurate creatinine assessment requires consideration of these biological and temporal factors.