Abnormal diurnal changes in in-vivo platelet activation in patients with atherosclerotic diseases

We measured the urinary excretion of beta-thromboglobulin in timed urine samples collected by 2 groups of healthy volunteers, (group I, n = 20, mean age 34 years, group II, n = 15, mean age 64 years) and by patients (n = 40) with symptomatic atherosclerotic diseases. Older healthy subjects were found to excrete high amounts of BTG in comparison to young subjects (302.25 +/- 50.61 vs 219.65 +/- 59.31 ng/day, P less than 0.05). Higher (P less than 0.01) levels of urinary BTG were observed in patients with coronary (427.61 +/- 179.96 ng/day), cerebral (422.13 +/- 223.2 ng/day) and peripheral (454.16 +/- 269.05 ng/day) arterial diseases and in diabetic patients with diffuse vascular complications (613.71 +/- 253.07 ng/day). The diurnal variability of BTG excretion, measured as coefficient of variation (C.V. %) of the mean daily excretion rate, was higher (P less than 0.001) in atherosclerotic patients (70.59 +/- 26.57) as compared with the similar values observed in the control groups of young (32.05 +/- 14.54) and older subjects (26.38 +/- 8.4). Comparable diurnal variabilities of the creatinine excretion rate were observed in the control groups and in patients. These data indicated that in vivo platelet activation may occur in atherosclerotic patients with a distinctive high fluctuation rate.