Abnormalities of iodine and protein in the thyroid of patients with Hashimoto's thyroiditis.

Iodine content, protein content and percentage of thyroglobulin to total protein in the thyroid glands were studied in two groups of 10 patients with Hashimoto's thyroiditis (5 euthyroid and 5 hypothyroid patients) and in 6 normal subject. Iodine content was significantly decreased in both hypothyroid (24 +/- 29 microgram/g wet weight of thyroid tissue, mean +/- S.D., p less than 0.01) and euthyroid (96 +/- 52, p less than 0.01) groups of Hashimoto's thyroiditis compared with those in controls (779 +/- 37). The value of hypothyroid group was significantly smaller than that of euthyroid group (p less than 0.05). A significant negative correlation was obtained between thyroidal iodine content and serum TSH (r = -0.68, y = -0.41 chi + 55.6, p less than 0.05). Thyroidal protein and percentage of thyroglobulin to total thyroidal protein were also decreased in Hashimoto's thyroiditis compared with controls, while there was no difference between euthyroid and hypothyroid groups in these values. The percentage of thyroglobulin-bound 131I obtained by in vitro iodination of thyroglobulin in Hashimoto's thyroiditis appeared to be decreased in 2 cases of hypothyroid group. Some immunological reaction occurring in Hashimoto's thyroiditis may change the structure of thyroglobulin and in turn the normal iodination of thyroglobulin may be disturbed.