Autoimmune thyroid disease in primary Sjögren's syndrome.

PURPOSE : To evaluate the prevalence of autoimmune thyroid disease and thyroid dysfunction in patients with primary Sjogren's syndrome. PATIENTS AND METHODS : Thyroid function of 33 patients with primary Sjogren's syndrome was clinically and biochemically evaluated. Thyroid hormones and autoantibodies against thyroid peroxidase, thyroglobulin, and thyroid hormones were measured. RESULTS : Autoimmune thyroid disease and thyroid dysfunction were found in 15 cases (45%) : autoimmune thyroiditis in 8 (24%) ; autoimmune hyperthyroidism in 2 (6%) ; and reversible iodine-induced hypothyroidism in the remaining 5 (15%). One or more of the evaluated autoantibodies were detected in 8 euthyroid patients (24%). Overall, the prevalence of autoantibodies against thyroid peroxidase, thyroglobulin, thyroxine, and triiodothyronine was 45%, 18%, 42%, and 36%, respectively. CONCLUSIONS : The high prevalence of autoimmune thyroid disease and thyroid dysfunction found in primary Sjogren's syndrome, using sensitive immunologic and thyroid function tests, suggest that both diseases are more frequently associated than it was previously thought, and should be sought clinically and by laboratory tests in all patients with primary Sjogren's syndrome.