Significant elevation of protein C and protein S levels in thrombotic disorders by low dose danazol

Six patients (three males and three females), mean age 35.2 years (range 31-43 years), with extensive venous thrombosis were studied. Initial laboratory data indicated that all patients had normal antithrombin III (ATIII), four patients had low protein C (PC), three patients had low protein S (PS) and two patients had low plasminogen. Four patients had high fibrinogen and all patients had reduced tissue-type plasminogen activator activity, elevated tissue plasminogen activator inhibitor and low fibrinolytic activity. All patients were treated with danazol, 5-7 mg/kg orally once daily. In all patients there was significant elevation of ATIII, PC, PS, and plasminogen, reduction in plasma fibrinogen and PAI and enhancement of fibrinolysis. During the 12-36 months period of follow-up, there were no symptoms or signs that suggested recurrence of thrombosis. Apart from weight gain of 5-10 kg and disturbed menstrual cycle in two women, no major side effects were seen. These data suggest that danazol is potentially useful therapy that may increase levels of natural anticoagulants in patients with thrombotic illnesses in which ATIII, PC and PS are low or normal. Further studies are needed to confirm these observations.