The Effect of Diurnal Variation on Laboratory Tests

Objective: Commonly used biochemical tests in blood samples may be measured at any time of day. This study investigated the existence and clinical significance diurnal variations some routine parameters to facilitate accurate reliable decision-making diagnosis follow-up.
 Materials Methods: Blood were collected from 17 healthy volunteers who 18-50 years age (11 men, 6 women) on same day 9:00 am, 12:00 3:00 pm, 6:00 pm. Samples am regarded as baseline. The results 19 obtained 12.00 3.00 6.00 pm statistically clinically compared with 9.00 baseline sample. 
 Results: Total protein, creatinine, aspartate transaminase, alanine alkaline phosphatase gamma glutamyl transferase showed no significant variation within day, but changes observed levels glucose, total cholesterol, HDL-cholesterol, triglyceride, bilirubin (TBIL), direct (DBIL), albumin, urea nitrogen, uric acid, sodium, potassium, chloride amylase. Especially, BUN changed by maximum 20-30%, TBIL, DBIL triglyceride 40-50% day.
 Conclusion: our suggest that clinicians should consider timing sampling BUN, during treatment follow-up. Sampling throughout seems pose problem for other limited variation.