Subacute thyroiditis during interferon-alpha therapy for chronic hepatitis C

A 34-year-old woman with chronic hepatitis C received interferon-alpha (IFN-alpha) therapy. Her thyroid function was normal and thyroid autoantibodies were negative before treatment. Four months after the beginning of the therapy she presented a clinical course of thyroiditis with a transient thyrotoxicosis. The diagnosis of subacute thyroiditis was confirmed by laboratory, ultrasonography, radioiodine scanning and fine needle aspiration findings. Thyroid autoantibodies were persisting negative. She suspended IFN-alpha therapy and she started non steroidal anti-inflammatory agents and beta-blockers. Latent hypothyroidism subsequently developed, but L-thyroxine therapy resulted in a rapid normalization of thyroid function tests.