Subacute thyroiditis during treatment with combination therapy (interferon plus ribavirin) for hepatitis C virus

Autoimmune thyroiditis has been frequently reported during interferon monotherapy for hepatitis C, but there are few reports concerning subacute thyroiditis. Recently, combination therapy of IFN plus ribavirin has become the preferred therapeutic schedule for chronic hepatitis C. Similarly to interferon monotherapy, there are no reports concerning subacute thyroiditis during combination therapy. We described four episodes of subacute thyroiditis occurring in three patients during antiviral combination therapy. All patients had symptoms compatible with hyperthyroidism, which could be misdiagnosed as IFN side-effects. The antiviral treatment was continued in all three patients and thyroid function increased progressively with pharmacological treatment for hyperthyroidism. We concluded that subacute thyroiditis may be a complication of combination antiviral therapy and should be investigated in patients presenting with compatible symptoms, in order to differentiate from IFN side-effects.