Virologic factors related to interferon-α-induced thyroid dysfunction in patients with chronic hepatitis C

Abstract

Objective: Hepatitis C virus (HCV), being reported to be associated with a high prevalence of serological markers of autoimmunity in HCV-infected patients, and possibly sharing partial sequences in amino acid segments with thyroid tissue antigens, may be associated with interferon-α (IFN-α)-induced thyroid dysfunction in chronic hepatitis C patients. We conducted this study to clarify the issue. Design and Methods: One hundred and fifty chronic hepatitis C patients with normal baseline thyroid function were treated with IFN-α 2a, 2b and n1 (3-6 million Units three times weekly for 24 weeks). Pretreatment sera were tested for HCV genotype and HCV RNA levels. Serum thyrotropin, total thyroxine and free thyroxine index were performed every 4 weeks for 24 weeks followed by every 8 weeks for another 24 weeks. Results: Twenty-one (14.0%) patients developed early thyroid dysfunction (abnormal thyroid function during the first 3 months of therapy). Female gender, lower HCV RNA levels, IFN-α n1 and a lower IFN-α dose were significantly associated with early thyroid dysfunction. On multivariate analysis, gender, IFN-α preparation and HCV RNA levels were the significant factors associated with early thyroid dysfunction. Seven (4.7%) patients developed thyroid dysfunction during the second 3 months of IFN-α therapy. Taken together, 18.7% patients developed thyroid dysfunction. Female, mixed HCV genotype infection and lower HCV RNA levels were significantly associated with thyroid dysfunction. However, only gender remained significantly associated with IFN-α-induced thyroid dysfunction in multivariate analysis. Conclusions: The virologic features of HCV may be associated with thyroid dysfunction in chronic hepatitis C patients treated with IFN-α. Nevertheless, gender still plays the most important role in IFN-α-induced thyroid dysfunction.