Danazol treatment for paroxysmal nocturnal hemoglobinuria

Danazol was administered to two patients with paroxysmal nocturnal hemoglobinuria (PNH) with a dramatic effect on the hematological findings. The patients, 31- and 41-year-old females, were initially diagnosed as having aplastic anemia, and were initially treated with anabolic steroid and immunosuppressive therapy, respectively. Sugar water and Ham tests turned positive at the start of danazol therapy in the former patient and after two months in the latter patient. This drug produced a dramatic improvement in the hemoglobin level and the platelet count and showed few side effects in the patients. A possible mechanism of action of danazol for PNH is briefly discussed.