Temporal relationship between the appearance of thyroid autoantibodies and development of destructive thyroiditis in patients undergoing treatment with two different type-1 interferons for HCV-related chronic hepatitis: a prospective study.

In this prospective study we performed repeated evaluations of thyroid status in patients undergoing treatment with different preparations of recombinant interferons (IFNs), in order to identify early markers of thyroid dysfunction. Moreover, we aimed to investigate whether the development of thyroid dysfunction was related to the appearance of thyroid autoimmunity. Our study included 51 consecutive patients without pre-existing thyroid disease, admitted to our hospital for Hepatitis C virus (HCV)-related chronic hepatitis. Thirty-six patients (Gr. A) were treated with IFN-alpha 2b plus ribavirin (RIBA), whereas 15 patients (Gr. B) underwent treatment with IFN-alphacon-1 (CIFN) plus RIBA. Thyroid autoimmunity and function were prospectively evaluated before, every month during treatment and for 6 months after IFN withdrawal. At study entry, all patients were euthyroid and negative for thyroid autoantibodies. In Gr. A, 10 patients developed thyroid autoimmunity after a median period of 3 months (range: 1-6) treatment with IFN-alpha+RIBA. At the time of appearance of thyroid autoantibodies, 4 patients developed destructive thyrotoxicosis (overt in one case, subclinical in 3 cases), while other 4 patients showed a high reduction of serum TSH levels (median decrease: -75.7%, range: -61.9- -84.2), which reached the low values of normal range. After a median period of 2 months (range: 1-3) from these biochemical abnormalities, 6 patients continuing antiviral treatment developed hypothyroidism (overt in 3 cases and subclinical in the other 3). In Gr. B, 5 patients developed thyroid autoimmunity after a median period of 3 months (range: 2-10) of treatment with CIFN+RIBA. Soon after the appearance of thyroid autoantibodies, all patients developed an overt thyrotoxicosis (with hyperthyroidism in 2 cases). Antiviral treatment was discontinued in all 5 cases. Thereafter, thyroid function recovered spontaneously without significant modifications of serum TGAb and TPOAb levels until the end of the study. In conclusion our prospective study demonstrated that: 1) the appearance of thyroid autoantibodies during treatment with IFN was accompanied in most cases by the occurrence of a destructive process in the thyroid gland; 2) The clinical expression of destructive thyroiditis was more evident in patients treated with CIFN than that in patients treated with IFN; 3) The thyroid clinical outcome of these patients was strictly correlated to the continuation of cytokine treatment.