Interferon-Alpha-Induced Thyroid Dysfunction in Patients with Chronic Active Hepatitis C: A Transient, Reversible and Self-limited Dysfunction

To survey the prognoses of interferon-alpha (IFNα)-induced thyroid dysfunction, a total of 100 patients (49 males and 51 females) with biopsy-proven chronic active hepatitis C were studied. Either during or after IFNα therapy, 29 patients (33.7 %) revealed suppression/elevation of thyroid stimulating hormone (TSH) or both, transient thyrotoxicosis (TSH less than 0.1 μU/ml) or transient hypothyroidism (TSH 5.0-190.95 μU/ml). However, the thyroid function normalized without supplementation of the thyroid hormone in the follow-up period. In the same period, one of the 14 control patients (7.1 %) developed thyroid dysfunction. Thyroid abnormalities developed significantly more in patients with IFNα therapy than in those without IFNα therapy. The findings suggest that the occult autoimmune disorder becomes overt with IFNαtreatment in patients with pre-existent autoimmune thyroid disease. IFNα-induced thyroid dysfunction is transient, reversible and self-limited. It is not necessary to discontinue IFNα therapy when thyroid dysfunction develops.(Internal Medicine 37: 27-31, 1998)