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Circannual rhythms of laboratory parameters in serum of elderly subjects. Evaluation by cosinor analysis
Insights
Elderly individuals exhibit seasonal variations in many blood markers, including glucose and electrolytes. These annual rhythms in lab values are generally minor but may hold physiological significance.
Area of Science:
- Gerontology
- Clinical Chemistry
- Chronobiology
Background:
- Laboratory test results can fluctuate over time.
- Understanding these fluctuations is crucial for accurate medical interpretation.
Purpose of the Study:
- To investigate circannual variations in serum concentrations of various blood markers in elderly individuals.
- To assess the potential diagnostic and physiological implications of these seasonal rhythms.
Main Methods:
- Analysis of 230 24-hour blood profiles from 189 elderly subjects (76 ± 8 years).
- Blood samples were collected at 4-hour intervals across all four seasons.
- Circadian means were analyzed for circannual variations using single cosinor analysis.
Main Results:
- Statistically significant circannual variations were observed in serum concentrations of albumin, total bilirubin, calcium, chloride, creatine phosphokinase (CPK), glucose, lactate dehydrogenase (LDH), potassium, sodium, triglycerides, and uric acid in men and/or women.
- The magnitude of these seasonal rhythms was generally small, posing minimal diagnostic challenges in current laboratory medicine.
Conclusions:
- Significant circannual rhythms exist for numerous blood markers in the elderly.
- These seasonal variations, while often minor, may indicate underlying physiological or pathobiological processes.
- Quantifying these rhythms is important for understanding normal variability in laboratory values and potentially as health indicators.
Abstract:
A total of 189 elderly subjects 76 +/- 8 years of age were studied in 230 24-hour profiles consisting of six blood samples collected at 4 hour intervals. The sampling sessions were spread over all four seasons. The circadian means were analyzed by single cosinor analysis for the presence of circannual variations. Statistically significant circannual variations were found in men and/or in women in the serum concentrations of: albumin, total bilirubin, calcium, chloride, CPK, glucose, LDH, potassium, sodium, triglycerides, and uric acid. Only in few functions is the extent of the circannual rhythms in the variables presented here large enough to present potential diagnostic problems in today's practice of laboratory medicine. However, the seasonal variations in metabolic functions, or if endogenous in nature, circannual rhythms may be of physiologic and pathobiologic importance. There is a need to quantify certain of these rhythms as a predictable portion of variability in laboratory values, and presumably as an indicator of human health.