Latent autoimmune thyroiditis in untreated patients with HCV chronic hepatitis: a case-control study

In order to establish a relationship between Hepatitis C virus (HCV) chronic infection and autoimmune thyroiditis, 97 untreated patients with biopsy-proven HCV chronic hepatitis and 97 controls were studied. An ultrasound examination of the thyroid and an assay of serum thyroid-stimulating hormone (TSH), thyroid hormones and anti-thyroid antibodies were performed in all cases. The overall prevalence of thyroid abnormalities was higher in patients than in controls (17 vs. 4%, P<0.01) and the prevalence of anti-thyroid antibodies was significantly different between the two groups (P<0. 02). HCV patients with (n=13) compared to HCV patients without anti-thyroid antibodies (n=84) were older, predominantly female, and more frequently had increased serum TSH levels or a hypoechogenic pattern of the thyroid gland, while Knodell's score and prevalence of cirrhosis were similar. Latent autoimmune thyroiditis is more frequent in untreated HCV patients than in controls. This finding raises questions about the mechanism of autoimmunity induced by HCV and provides an explanation for the high rate of overt autoimmune thyroiditis during interferon treatment in these patients.