Immunological and clinical characterization of patients with untreated euthyroid and hypothyroid autoimmune thyroiditis. Antibody spectrum, response to TRH and clinical study.

In a region of endemic goitres, 200 untreated patients in whom thyroid microsomal (MCHA) and/or thyroglobulin (TGHA) antibodies have been detected were analyzed and other organ specific autoantibodies were tested. Thyroid function was assessed by a TRH test in all of them. Patients with previous thyroid disease and patients with clinical or biochemical signs of thyrotoxicosis were excluded. In 58 (29%) of the patients diseases coexisted in which a high incidence of autoimmune reactions has been recognized. In the absence of the corresponding clinical disease, 13.7% of the patients had antibodies to parietal cells of the stomach, 3.1% had antibodies to adrenal cortex, 1% to steroid producing gonadal cells, 1% to pancreatic islet cells, and 0.5% of the patients had antibodies to striated muscle fibrils. The incidence of associated organ-specific autoantibodies was no higher in patients with hypothyroidism (34.6%) compared with patients who had a normal thyroid function (27.9%). The determination of a 'significant' thyroid antibody titre is discussed. In 24.5% of the 200 patients a form of hypothyroidism was recognized. Fifty of the patients with TGHA titres greater than or equal to 6400, and 56.2% of those with MCHA greater than or equal to 102 400 were hypothyroid. Patients with such titres of thyroid antibodies should be examined and followed up. Patients with associated islet cell or adrenal antibodies should be reinvestigated and followed up observing their glucose tolerance and adrenocortical function, respectively.