Methimazole-induced agranulocytosis preceded by transient granulocytopenia. A case report.

A 36-year-old patient, euthyroid under methimazole treatment, was admitted because of an active Graves' ophthalmopathy and found to have a transient granulocytopenia. Forty-five days after this episode she developed classical agranulocytosis because of which the methimazole was stopped. The agranulocytosis occurred more than 20 months after the initiation of antithyroid drug therapy. Other causes for the initial phase of granulocytopenia were not found.