Interferon-Alpha-Induced Destructive Thyroiditis Followed by Graves' Disease in a Patient with Chronic Hepatitis C: A Case Report

Interferon-induced thyroiditis (IIT) is a major clinical problem for patients receiving interferon-alpha (IFN-α) therapy. But, destructive thyroiditis followed by Graves' disease associated with IFN-α therapy is very rarely reported. Herein, we report a rare case of pegylated IFN-α (pegIFN-α) induced destructive thyroiditis followed by Graves' disease in a patient with HCV infection. A 31-yr-old woman suffered from chronic active hepatitis C and was treated with pegIFN-α and ribavirin for 12 months. Results of a thyroid function test and autoantibody levels were normal before IFN-α therapy was initiated. Destructive thyrotoxicosis appeared seven months after the initiation of IFN-α therapy, followed by Graves' thyrotoxicosis two months after the cessation of therapy. The diagnoses of destructive thyroiditis and Graves' disease were confirmed by the presence of TSH receptor antibodies in addition to Tc-99m scintigraphy findings. The patient's antithyroglobulin antibody titer increased gradually during IFN-α therapy and remained weakly positive after IFN-α therapy was discontinued.