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Day-to-day intraindividual reliability and interindividual differences in monoamines excretion
F Curtin1, J P Walker, P Schulz
1Department of Psychiatry, Geneva University, IUPG, Switzerland.
Journal of Affective Disorders
|June 5, 1996
Summary
This study reveals significant day-to-day variations in urinary monoamine excretion among healthy men. These findings highlight the importance of considering biological variability in dopamine and other catecholamine measurements.
Area of Science:
- Biochemistry
- Clinical Chemistry
- Human Physiology
Background:
- Urinary monoamine levels are crucial biomarkers for various physiological and pathological states.
- Understanding biological variation is essential for accurate interpretation of these biomarkers.
- Previous studies have not fully delineated the day-to-day variability in multiple urinary monoamines.
Purpose of the Study:
- To quantify intraindividual (day-to-day) and interindividual variability in the urinary excretion of key monoamines and their metabolites.
- To assess the reliability of these measurements in normal men.
- To establish reference ranges for biological variation in catecholamine and indoleamine excretion.
Main Methods:
- Collected urine samples from 44 healthy adult males over two consecutive nights.
- Analyzed urine for the excretion levels of dopamine, norepinephrine, epinephrine, normetanephrine, metanephrine, MHPG, VMA, HVA, and 5-HIAA.
- Calculated interindividual and intraindividual coefficients of variation.
- Determined intraclass correlation coefficients to assess measurement reliability.
Main Results:
- Significant interindividual variability was observed across most measured monoamines, with coefficients of variation ranging from 18.3% (dopamine) to 85.3% (epinephrine).
- Intraindividual variability was also substantial for several compounds, including norepinephrine (39.9%) and epinephrine (45.9%), but lower for dopamine (8.5%) and normetanephrine (10.3%).
- High reliability was confirmed, with intraclass correlation coefficients indicating consistent measurements within individuals over the short term.
Conclusions:
- Urinary monoamine excretion exhibits considerable day-to-day biological variation in healthy men.
- Dopamine and normetanephrine showed the lowest intraindividual variability, suggesting higher reliability for these specific analytes.
- These findings underscore the need to account for biological variability when interpreting urinary monoamine levels in clinical and research settings.