Daily modifications of plasma fibrinogen platelets aggregation, Howell's time, PTT, TT, and antithrombin II in normal subjects and in patients with vascular disease.

The possibility of occurrence of daily variations in blood fibrinogen levels, platelets aggregation. Howell's time values and values for PTT, TT and antithrombin III was explored in 10 healthy subjects and in 10 patients with vascular disease. In normal subjects blood fibrinogen, platelets aggregation in ADP, PTT, Howell's time and TT values showed statistically significant daily variations, while the AT III values showed no significant variations over the 24-h cycle. In patients with vascular disease, on the other hand, the daily variations of the fibrinogen blood levels, of the maximum amplitude of platelets aggregation and of the Howell's values were not detected. In fact, the first two parameters remained consistently high and the third parameter remained consistently low throughout the 24-h cycle. In contrast, the PTT as well as the TT values in these patients showed statistically significant daily variations but with time patterns different than those found in normal subjects. Also, unlike to what obtained in healthy subjects, the AT III values in patients with vascular disease showed highly significant variations over the period of 24-h.