High Prevalence of Thyroid Autoimmunity in Idiopathic Addison's Disease

Abstract

We have determined the incidence of autoimmune thyroid disorders in patients with Addison's disease. The material comprised 212 patients, 128 women and 84 men, aged 9-74 years. In 58 patients tuberculosis and in six patients other adrenal disorders were diagnosed. In the remaining 148 patients the auto-immune mechanism was the most probable cause of adrenocrotical insufficiency. In order to evaluate the thyroid abnormalities seen in patients with Addison's disease the T₃, T₄ (RIA), TSH (ELISA) and anti-thyroid autoantibodies were determined apart from routine clinical examination. Antimicrosomal, anti-thyroglobulin and anti-thyroperoxidase antibodies were measured in 91, 188 and 81 cases respectively. Thyrotoxicosis was diagnosed in 17 and primary hypothyroidism in 18 cases. Moreover, eight patients had evidence of subclinical hypothyroidism. The anti-thyroglobulin antibodies with titer ranging from 1 : 80 to 1 : 10 000 were detected in 66 patients, whereas antimicrosomal antibodies were found in 51 patients at a titer ranging from 1 : 80 to 1 : 9720. Autoantibodies against thyroid peroxidase were found in sera of 67 patients, with titer ranging from 1 : 2000 to 1 : 25 6000.

Key Words:

• Addison's disease
• thyroid autoantibodies
• thyroid autoimmune disorders
• antithyroid peroxidase antibodies