Danazol is a synthetic steroid hormone structurally resembling a group of natural hormones (androgens)found in the body. Danazol has immune modifying activity and is effective in treatment of blood disorders with low platelet counts such as idiopathic thrombocytopenic purpura (however FDA has not yet approved danazol for this disorder). A study of danazol in conjunction with plasma exchange for thrombotic thrombocytopenic purpura showed that danazol decreased the number of plasma exchanges required by approximately 80% and reduced the time needed to control the disease. It's not clear how danazol works in TTP. It is not approved by the FDA for the treatment of TTP.