Abstract
Ingbar et al. reported that progressive failure of thyroid function, possibly due to concomitant chronic thyroiditis, developed in some patients with diffuse toxic goiter who had been successfully treated with antithyroid drugs for many years previously. However, the histological characteristics of the thyroid glands of these patients were not discussed in their report. In the present study, the thyroid functions and histological features of the thyroid glands were examined in 77 patients who had been diagnosed as having Graves' disease between 1962 and 1971.
Measurements of the thyroid functions revealed that, of the 77 cases, 41 (53.2%) were biochemical euthyroid, 30 (39.0%) were hyperthyroid, 2 (2.6%), were T3-toxicosis, 3 were hypothyroid and 1 was subclinical hypothyroid. Abnormal responses to TRH were observed in 8 of 30 euthyroid cases. Non- or hypo-response (peak value of TSH<6.2μU/ml) was observed in 5 (16.7%) and hyper-response (peak value of TSH>35μU/ml) was observed in 3 cases (10.0%). A T3 suppression test showed that three of 11 euthyroid cases examined were non-suppressible. The remaining 8 suppressible cases showed responsiveness to TRH without exception.
Histological examination of the specimen (23 cases) obtained by either subtotal thyroidectomy (14 of 30 hyperthyroid cases) or needle biopsy revealed that 14 samples had diffuse epithelial hyperplastic goiter (d.e.h.), 7 had chronic lymphocytic thyroiditis (c.l.t.) and 2 had normal thyroid tissue (n.t.t.). All cases with d.e.h. and 1 case with c.l.t. were accompanied by hyperthyroidism. Four cases with c.l.t. and 2 cases with n.t.t. were accompanied by euthyroidism. T3-toxicosis and subclinical hypothyroidism were evident in 1 case with c.l.t. respectively. 40.6% and 90.6% of hyperthyroid patients and 53.7% and 92.6% of euthyroid patients were positive in a thyroid test and microsome test respectively. Titers of the microsome test of the euthyroid patients were significantly higher than those measured in 1972.
These results suggest that after medical treatment, 1) most of the patients with Graves' disease who had a prolonged clinical remission had c.l.t. in thyroid tissue, 2) some patients with Graves' disease become hypothyroid at the terminal stage of chronic thyroiditis.
