Aplastic anaemia caused bythiamazole: A case report

Antithyreoid drugs are known causative agents of agranulocytosis and, in rare cases, aplastic anaemia as well. This is a case report of a female patient with secondary aplastic anaemia developed two years after continual use of thiamazole. She suffered from exhaustion and massive epistaxis. Physical examination revealed pale skin and mucous membranes, skin hematomas (body and legs) and high body temperature--39 degrees C. At admission, her blood film revealed pancytopaenia with 75 g/l hemoglobin concentration, 1.0 x 10(9)/l leukocytes and severe thrombocytopaenia--7.0 x 10(9)/l. Differential count showed 91% of lymphocytes, 1% of monocytes and only 8% of neuthrophils. Bone marrow cytology and pathohistologic findings revealed severe hypocellularity, replaced with fat cells and only 10% of active hematopoietic tissue. In the acute phase of illness, in vitro growth of bone marrow progenitors was completely absent. Treatment was initiated with prednisone and danazol. During that time, she suffered from epistaxis, gastro-intestinal bleeding and herpes infection. Due to therapeutic failure cyclosporine A was added after 21 days. There upon, slow recovery ensued. After two months, she was discharged from hospital with stable blood film findings (HB 83 g/l, WBC 4.6 x 10(9)/l, and PLT 30.0 x 10(9)/l). She was forbidden thiamazole for her life time. After recovery from the acute phase of illness, in vitro haematopoietic precursor cells examination was repeated. The number of CFU-E colonies stimulated with 1 IU EPO was decreased in comparison with the control values. Upon adding 100 micro/l of thiamazole (5 mg/ml concentration e.g. 500 mg per culture), the growth of CFU-E was completely prevented, followed by marked cytotoxicity signs. The treatment including low doses (5 mg/ kg body weight daily) of cyclosporine A administration was continued on outpatient basis. After one year, blood film showed almost normal results with 120 g/l hemoglobin concentration, 4.3x10(9)/l leukocytes and mild thrombocytopaenia 72.0 x 10(9)/l. She was transfusion free.