Intra-individual variation in commonly analyzed serum constituents

Area of Science:

• Clinical Biochemistry
• Human Physiology
• Analytical Chemistry

Background:

• Understanding diurnal variations in serum analytes is crucial for accurate clinical interpretation.
• Previous studies have indicated temporal fluctuations in certain blood components, but comprehensive analysis across multiple time points and days is needed.

Purpose of the Study:

• To investigate the diurnal and day-to-day variability of 27 common serum constituents in healthy adults.
• To identify which serum analytes exhibit statistically significant temporal variations.

Main Methods:

• Blood samples were collected from 20 healthy volunteers at three time points (0830, 1230, 1630 hours) over four weekly intervals.
• Concentrations of 27 serum constituents were measured using standard laboratory assays.
• Statistical analysis was performed to assess diurnal and day-to-day variations (p ≤ 0.01).

Main Results:

• Twelve of the 27 serum constituents exhibited statistically significant time-dependent variations.
• Consistent temporal patterns were observed for urea, creatinine, phosphate, zinc, bilirubin, triglyceride, total protein, and albumin.
• Potassium, iron, zinc, and bilirubin showed the greatest magnitude of variation, with within-day changes exceeding day-to-day changes for potassium, phosphate, and zinc.

Conclusions:

• Significant diurnal variation exists for a subset of common serum analytes in healthy individuals.
• Specific analytes like urea, creatinine, and albumin demonstrate consistent temporal patterns, impacting interpretation.
• The findings highlight the importance of considering time of day and day-to-day variability in serum sample collection and analysis.