[Allopurinol induced pancytopenia in a patient with myeloproliferative disorder]

We reported a rare case of pancytopenia caused by allopurinol. A 61-year-old man was first admitted in May 1993, because of thrombocytosis. He had suffered from chronic glomerulonephritis. He was administered allopurinol for hyperuricemia from March 1993. On first admission the laboratory findings revealed leukocytosis (10,100/microliter) and thrombocytosis (971 x 10(3)/microliter) in the peripheral blood. Myelofibrosis was strongly suspected due to increased number of MgK and reticular fiber in the bone marrow. Two months later, he readmitted due to pancytopenia (WBC 1,300/microliter, Hb 6.2g/dl, Plt 10 x 10(3)/microliter). His bone marrow showed markedly hypocellular. Because we suspected that pancytopenia was induced by allopurinol, we discontinued allopurinol and administered oxymetholone, G-CSF, and EPO, WBC, RBC, and platelet count had been recovered about one and half months later. In vitro co-culture indicated that CFU-G, E, and Meg in the bone marrow cells after recovery from pancytopenia were markedly suppressed in the presence of patient's serum and oxipurinol. Pancytopenia due to allopurinol was reported to be rare, and some authors showed that it will sometimes be fatal. Because pancytopenia of this case had been recovered in a relatively short time with cytokine therapy, it was thought to be effective for pancytopenia due to drug like this case.