Autoimmune thyroid disease and antiphospholipid antibodies

Objective: Autoimmune thyroid disease (ATD) is associated with circulating autoantibodies reactive with epitopes on thyroid tissue and that are though t to be pathogenic in the development of these diseases. Antiphospholipid a ntibodies (APLA) are a family of immunoglobulins that recognize a variety o f plasma proteins in association with anionic phospholipids. These antibodi es may lead to a number of clinical syndromes including venous and arterial thromboses, thrombocytopaenia, and recurrent fetal loss. We have studied t he prevalence of APLA in patients with ATD and have determined the prevalen ce of the APLA syndrome among APLA-positive patients. Design: The study was a retrospective survey of patients with autoimmune thyroid disease attendi ng the endocrinology clinic of a tertiary care academic hospital. Patients and Measurements: One hundred and thirty patients with autoimmune thyroid d isease from the endocrinology clinic at our hospital were studied, 84% had chronic thyroiditis and 16% had Graves' disease. Free T4 and thyroid stimul ating hormone (TSH) levels, antimicrosomal and antithyroglobulin antibodies , and an antiphospholipid antibody test were performed on all subjects. Res ults: 43% of patients with chronic thyroiditis and 43% of patients with Gra ves' disease were APLA positive, with an overall rate of 43% APLA positivit y among patients with ATD. Of the 56 patients that were APLA positive, fort y-eight (86%) had APLA of the IgG subtype, four (7%) had IgM antibodies, an d nine (16%) had both IgG and IgM antibodies. None of the patients had clin ical evidence of the APLA syndrome. Conclusions: We conclude that the preva lence of APLA in ATD is increased compared to healthy individuals but that this is likely to be an epiphenomenon, However, prolonged follow up is nece ssary in order to determine the true clinical significance of these antibod ies in ATD patients. Am. J, Hematol, 64:73-75, 2000, (C) 2000 Wiley-Liss, I nc.