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Original Investigation
July 13, 1998

Increased Risk of Autoimmune Thyroid Disease in Hepatitis C vs Hepatitis B Before, During, and After Discontinuing Interferon Therapy

Author Affiliations

From the Endocrine and Metabolic Unit (Drs Fernandez-Soto, Gonzalez, Escobar-Jimenez, and Vazquez), the Departments of Pediatrics (Dr Ocete) and Radioisotopes (Dr Olea), and the Digestive Unit (Dr Salmeron), Universitary Hospital, Granada, Spain.

Arch Intern Med. 1998;158(13):1445-1448. doi:10.1001/archinte.158.13.1445

Background  Thyroid gland dysfunction has been reported to occur with variable frequency during interferon alfa (IFN-α) therapy in patients with the hepatitis C virus (HCV). We prospectively evaluated if the prevalence of autoimmune thyroid disease in patients with HCV differs from that in patients with the hepatitis B virus (HBV) before, at the end of, and 6 months after stopping treatment with IFN-α.

Methods  One hundred thirty-four patients with HCV and 41 patients with HBV were studied. Measurements of serum free thyroxine, free triiodothyronine, thyrotropin, thyroid peroxidase antibodies (TPOAbs), thyroglobulin antibodies (TgAbs), and thyrotropin-binding inhibitory immunoglobulin were performed.

Results  Positive levels of TPOAb and TgAb were found in 20% and 11% of patients with HCV compared with 5% and 3% of patients with HBV, respectively. At the end of IFN-α therapy, thyroid gland dysfunction was more prevalent in patients with HCV (12%) compared with those with HBV (3%), with thyrotropin levels significantly higher in the HCV group (P=.03). Titers of TPOAb, TgAb, and thyrotropin-binding inhibitory immunoglobulin increased significantly (P=.02, P=.04, and P=.02, respectively) at the end of IFN-α therapy in patients with HCV but not in those with HBV. Patients who developed thyroid gland dysfunction were predominantly female (P=.03), had decreased levels of free triiodothyronine (P<.001), and had a higher prevalence of TPOAb (P=.03) before treatment with IFN-α. Thyroid gland dysfunction was reversed in 60% of those with HCV 6 months after discontinuing treatment with IFN-α.

Conclusions  Patients with HCV are more susceptible than patients with HBV to autoimmune thyroid disease. Systematic screening of thyroid gland function and TPOAb titers in all patients with HCV before, during, and after IFN-α therapy appears warranted. This precaution is not necessary for patients with HBV.