Ten-year follow-up study of thyroid function in euthyroid patients with simple goiter or Hashimoto's thyroiditis.

In an attempt to study the natural course of Hashimoto's thyroiditis and simple goiter, 74 euthryroid patients with Hashimoto's thyroiditis and 212 patients with simple goiter were followed for 10 years. In 204 patients with simple goiter (96.2%) it remained as a simple goiter throughout the observation period, whereas 8 patients (3.8%) later had Hashimoto's thyroiditis as evidenced by the appearance of circulating thyroid autoantibodies. These 8 patients had HLA typing significantly different from that of control subjects. None of the patients with simple goiter had hyperthyroid Graves' disease despite the fact that 17.5% of those patients had mild to moderate exophthalmos with either Moebius' sign or von Graefe's sign. In contrast, 12 patients with Hashimoto's thyroiditis (16.2%) had exophthalmos with Moebius' sign and/or von Graefe's sign, and 4 of 12 such patients later had hyperthyroid Graves' disease. TSH binding inhibitory immunoglobulin was detected in 3 of 4 such patients with hyperthyroid Graves' disease. Forty-nine patients with Hashimoto's thyroiditis (66.2%) still remained euthyroid but 20 of those (27.0%) turned into hypothyroidism during the 10-year follow-up.