Preziati D, La Rosa L, Covini G, Marcelli R, Rescalli S, Persani L, Del Ninno E, Meroni PL, Colombo M, Beck-Peccoz P. Autoimmunity and thyroid function in patients with chronic active hepatitis treated with recombinant interferon alpha-2a. Eur J Endocrinol 1995;132:587–93. ISSN 0804–4643 The occurrence of thyroid abnormalities and the appearance of organ- and non-organ-specific autoantibodies during long-term recombinant interferon alpha-2a (IFN-α) therapy were studied in 86 and 51 consecutive outpatients with hepatitis C and B virus-related chronic active hepatitis (CAH-HCV and CAH-HBV), respectively. Most patients had longstanding community-acquired hepatitis. At baseline, 9.3% of CAH-HCV and 3.9% of CAH-HBV patients showed clinical and/or biochemical signs of thyroid dysfunction. The remaining patients were euthyroid, although anti-thyroid autoantibodies were found in 33/78 (42.3%) of CAH-HCV and in 5/49 (10.2%) of CAH-HBV patients. During IFN-α treatment, increased anti-thyroid autoantibody levels were seen in 40% of CAH-HCV initially negative patients, while they became detectable in no more than 10% of CAH-HBV patients. Interferon-α-induced hypo- or hyperthyroidism was recorded in 12 of 35 CAH-HCV patients treated for 12 months (34.3%). Only one CAH-HBV patient developed hyperthyroidism. High titers of anti-nuclear auto-antibodies (ANA) were recorded at enrolment in 5/36 (13.8%) of CAH-HCV and in 3/16 (18.7%) of CAH-HBV patients. Only one CAH-HCV patient displayed anti-parietal cell antibodies (PCA). After IFN-α treatment, ANA were found in 10/28 (35.7%) and PCA in 2/28 (7.1%) of CAH-HCV patients, while an additional CAH-HBV patient developed PCA, but not ANA. However, no signs of systemic autoimmune disease were recorded. In conclusion, more than half of the patients with chronic active hepatitis C, but only one-tenth of those with hepatitis B, displayed thyroid- and/or non-organ-specific autoantibodies prior to or during treatment with IFN-α. As most of the antibody-positive patients developed permanent thyroid disorders during IFN-α therapy, the risk of development of organ-specific autoimmunity should be assessed carefully and incorporated in the cost/effectiveness analysis in patients with longstanding hepatitis who are candidates for IFN-α treatment. Paolo Beck-Peccoz, Institute of Endocrine Sciences, Ospedale Maggiore IRCCS, Padiglione Granelli, Via F. Sforza 35, 20122-Milano, Italy