A patient with Graves' disease accompanied by bloody pericardial effusion

A hyperthyroid patient with bloody pericardial effusion is presented. He was hospitalized for severe dyspnea. Pericardiocentesis yielded 1.2 liters of bloody fluid. Biochemical, cytologic, and radiologic examinations failed to identify the etiology of the effusion. Upon normalization of thyroid function using antithyroid drugs, the pericardial effusion resolved without recurrence. The patient was diagnosed as Graves' disease, which rarely is complicated by bloody pericardial effusion. As it is rarely reported and not widely known, this association may be underdiagnosed.