Reversible, extremely severe hypothyroidism in a patient with chronic hepatitis C treated with interferon-alpha

A 55-year-old patient with chronic hepatitis C received interferon-alpha (IFN-alpha) therapy in March-August 1992. After a few months of treatment, easy fatigability, general malaise, nonpitting edema, and facial edema developed. After treatment for 22 weeks, the patient, with typical clinical features of myxedema, was referred to our outpatient clinic with undetectable serum levels of T4 (< 1.0 microgram/dL) and T3 (< 25 ng/dL) and a markedly elevated TSH level (217 microU/mL). The serum thyroglobulin concentration was also undetectable (less than 5 ng/mL), suggesting that thyroid function was completely abolished. Following supplementation therapy with L-thyroxine, all the symptoms gradually disappeared. The patient remained euthyroid for nearly 2 years at a daily oral dose of 100 micrograms L-thyroxine. To clarify whether the IFN-alpha-induced hypothyroidism was reversible, L-thyroxine was discontinued after obtaining informed consent. The patient thereafter remained in a euthyroid state, without any significant symptoms, for more than 11 months. The present case indicates that hypothyroidism induced by IFN-alpha treatment may be reversible, even if it has developed over a prolonged period and become severe, resulting in undetectable serum levels of T3, T4, and thyroglobulin.