Fever or a soar throat after start of antithyroidal drugs? A medical emergency.

We describe two patients who developed granulocytopenia (granulocyte count < 1.0 x 10(9)/1) after treatment with antithyroid drugs. Although, perhaps, an already known side-effect of these drugs, we present these cases in order to stay alert for this serious complication. The first patient developed granulocytopenia upon reinstitution of propylthiouracil after an uncomplicated first course of ATD-treatment. In the second case we report the use of granulocyte colony-stimulating factor (G-CSF) for treatment of a patient with methimazole-induced granulocytopenia. Furthermore, we discuss current concepts concerning pathophysiology, prevention and therapy.