[Effects of danazol on plasma levels of protein S C4b-binding protein]

In order to elucidate the response of protein S (PS) and C4b-binding protein (C4bp) to danazol, we investigated the serial changes in plasma levels of PS and C4bp during danazol administration in 4 patients with endometriosis. Both total and free PS levels were significantly increased at the time of 2 to 3 weeks after danazol administration as compared to the pretreatment values, while C4bp levels were not changed at all. These results imply that danazol administration to PS deficiency would produce a significant increase in the basal level of free PS, suggesting a potential adjunct to anticoagulant treatment in PS deficiency.