[Circadian variations of bilirubin in the blood]

A group of 12 presumably healthy subjects was standardized for 7 days with rest time extending from 22.00 to 05.00. Meals were scheduled at 08.00-08.30, 12.00-12.30, 17.30-18.00 and the amounts consumed were standardized and measured. Each subject was sampled at 4-hour intervals throughout one 24-hour period; this involved the measurement of body temperature, radial pulse, blood pressure. In addition a sample of blood was collected at each time point and subsequently total, direct and indirect bilirubin measurement was made on each sample of serum. All data were analized by macroscopic approach (chronograms) and by mean cosinor. A circadian rhythm is detected in total, direct and indirect serum bilirubin.