Hypothyroidism after thyroidectomy for Graves's disease: a search for an explanation

Out of 38 patients who had undergone subtotal thyroidectomy for Graves's disease seven to 20 years previously 15 developed hypothyroidism. In these 15 patients autoantibodies against thyroid cytoplasm were significantly more frequent than in the 23 euthyroid patients, though there was no difference in the prevalence of autoantibodies against thyroglobulin. Histological examination of the thyroid tissue removed at operation showed that significantly more plasma cells and lymphoid follicles with germinal centres were present in patients who subsequently developed hypothyroidism than in those who remained euthyroid. No differences in the amount of lymphocytic infiltration were seen in hypothyroid and euthyroid patients.The results suggest that B lymphocytes play a part in the development of postoperative hypothyroidism in Graves's disease. It is proposed that Graves's disease and Hashimoto's disease are different aspects of the same basic autoimmune process.