A 23-year-old woman with preexisting Graves' disease who received thiamazole treatment presented with fever, dysphagia, hyperthyroidism and leukopenia. With suspicion of thyreotoxicosis accompanied by drug-induced agranulocytosis she was successfully managed by plasmapheresis, G‑CSF administration and inhibition of periphereal conversion of thyroid hormones. In due course she underwent thyroidectomy. Thiamazole is frequently associated with drug-induced agranulocytosis. Long-term therapy with thiamazole requires critical evaluation and alternatives should be considered early. Plasmapheresis is an adequate treatment option to achieve normal thyroid hormonal status.
Keywords: Agranulocytosis; Graves’ disease; Plasmapheresis; Thiamazole, adverse effects; Thyrotoxicosis.