LONGITUDINAL-STUDY OF ANTIBODIES AGAINST THYROID IN PATIENTS UNDERGOING INTERFERON-ALPHA THERAPY FOR HCV CHRONIC HEPATITIS

Seventy-five patients (50 M, 25 Fl, affected by chronic hepatitis caus ed by hepatitis C virus (HCV), without clinically overt thyroid diseas e, underwent r-interferon (IFN)-alpha-2a treatment (3-6 MU, 3 times/we ek) for 12 months. They were tested for thyroid function and for thyro id autoantibodies before (A), 6 (B) and 12 (C) months after the beginn ing of treatment and after 6 (D) months off therapy. Antithyroglobulin antibodies (Tg-Ab) and TSH were measured by IRMA, antiperoxidase anti bodies (TPO-Ab), free T-3 (FT3) and free T-4 (FT4) by RIA, thyrotropin receptor antibodies (TR-Ab) by RRA. None of the patients showed TR-Ab positivity throughout the study. The number of the patients with one or both antithyroid antibodies progressively increased during treatmen t (A 10.7%; B 26.7%; C 45.3%) and decreased when off therapy (D 22.7%) with none of them positive for Tg-Ab alone (TPO-Ab 6.7%; Tg-Ab + TPO- Ab 16%). Tg-Ab increased during rIFN (median: A 29.0; B 35.0; C 73.0 U /ml) but decreased when off therapy (D 29.0 U/ml). Instead, TPO-Ab sig nificantly increased throughout the study (A 1.0; B 3.0; C 6.0; D 7.0 U/ml). However, some patients showed for the first time an appearance of antibodies when off therapy. Five patients showed both antibodies a nd thyroid dysfunction: 2 at B, 2 at C, and 1 at D. Only 1 developed m ild transient hyperthyroidism while the other 4 developed hypothyroidi sm, persistent however only in 1 case. Our study confirms that rIFN-al pha-2a frequently induces thyroid autoimmunity. TPO-Ab seems more usef ul than Tg-Ab in monitoring the immunological response. Thyroid dysfun ction (especially hypothyroidism and in females), always accompanied w ith the appearance of thyroid autoantibodies, is often transitory in s pite of not discontinued treatment. The pretreatment positivity for Tg -Ab was not associated with the subsequent development of thyroid dysf unction, therefore it cannot be considered a risk factor in IFN-alpha therapy. Finally, the appearance in some cases of TPO-Ab after stoppin g treatment suggests that the thyroid surveillance in these patients s hould be prolonged.