Graves disease or other causes of thyrotoxicosis are frequently associated with cytopenia. Although anemia is the most common, other cell lineage can be affected. Pancytopenia is a rare complication of thyrotoxicosis.
We report a case of a 33-year-old Chinese man who presented a nonsevere pancytopenia in the context of a newly diagnosed Graves disease. Restauration of euthyroid state led to progressive correction of pancytopenia.
Literature review shows other rare cases of pancytopenia. It is usually nonsevere with just extremely rare cases of transfusion reported. Evolution was always favorable after achievement of euthyroid state. Its mechanism remains poorly understood, especially because those patients have no vitamin or iron deficiency. The exact physiopathological process remains unclear but 2 causes seem to overlap: reduced production of hematopoietic cells from the bone marrow and increased destruction or sequestration of mature hematopoietic cells. Despite unclear mechanism, the presence of hematologic abnormalities including pancytopenia must not be considered as a contraindication to antithyroid drug therapy.