[Case of hyperthyroidism with pancytopenia].

A case of hyperthyroidism associated with pancytopenia has been reported. A 51-year-old woman was hospitalized for the investigation of struma, peripheral edema and fatigue. Hormonal studies revealed hyperfunction of the thyroid gland. Hematological examinations showed normocytic normochromic anemia, leukopenia and thrombocytopenia with hyperplastic bone marrow and increased serum iron levels. Elevations of the anti-thyroidal antibody and anti-microsomal antibody, and a decrease in CH50 titer were observed. A Coombs' test and anti-leukocytic antibody and anti-thrombocytic antibody tests were negative. The numbers of erythrocyte and thrombocyte were normalized after the administration of methimazole for three months as were the findings of the bone marrow and the serum iron level. However, leukopenia was maintained due to the effect of methimazole. It should be suggested that the etiology of pancytopenia might be due to hyperthyroidism. Although the mechanism of pancytopenia in a patient with hyperthyroidism is unclear, it might be related to the reduced life-span of whole blood components and/or partially to the autoimmune mechanism.