Clinical experience of treating Graves' hyperthyroidism complicated with malignancy-The possible role of potassium iodide for avoiding the risk of thionamide-associated neutropenia.

The treatment of Graves' hyperthyroidism (GD) complicated with malignancy is challenging, as anti-thyroid thionamide drugs (ATDs) and anti-cancer chemotherapy are both associated with a risk of neutropenia. Treatment with conventional ATDs, radioactive iodine (RAI) or potassium iodide (KI) was attempted in 8 patients with malignancy (34-80 years of age; 2 males and 6 females) in whom GD had been fortuitously diagnosed during a detailed systematic examination. Three patients requiring surgery were initially treated conventionally with methylmercaptoimidazole (MMI), MMI and KI or RAI (group A; one patient each). The patients became euthyroid on days 17-31 and underwent surgery on days 25-47. RAI therapy was administered to one patient after surgery. The patients were then treated with KI during chemotherapy. Five other patients who did not require surgery were initially treated with 100 mg KI monotherapy (group B). The serum free T