Two cases of hypothyroidism associated with alpha-interferon therapy.

Alpha-interferon was used for anti-cancer or anti-viral therapy in two patients with preexisting autoimmune thyroid disease and in seven patients with chronic viral hepatitis who had no history of thyroid dysfunction. Primary hypothyroidism developed in the two patients who had a history of autoimmune thyroid disease, while no changes in thyroid function were observed in the other seven patients. Modulation of the immune system by alpha-interferon may have been responsible for the development of hypothyroidism in these two patients. Therefore, autoantibodies to the thyroid and the thyroid function should be assessed in patients undergoing alpha-interferon therapy.