Follow‐up evaluation of thyroid function after thyroidectomy for thyrotoxicosis

One hundred fifty‐seven patients with hyperthyroidism treated by subtotal thyroidectomy 2–8 years previously were followed up with serum T 3 , T 4 , and TSH determinations. There was some difficulty in distinguishing the various groups of patients by thyroid function tests. However, it was determined that the percentages of patients with hyperthyroidism, euthyroidism, and hypothyroidism, based on T 3 values, were 3.2%, 89.7%, and 7.1%, respectively, whereas 5.8%, 41.6%, and 53.1% were hyperthyroid, euthyroid, and hypothyroid by TSH criteria. Subclinical hypothyroidism, that is, increased TSH levels but normal T 3 and T 4 levels, accounted for the major discrepancy in these results. Subclinical hypothyroidism is more sensitive to disclosure by the TRH stimulation test. However, the incidence and severity of hypothyroidism after thyroidectomy are lower and milder than after 131 I treatment. The recurrence rate is less than that after the administration of antithyroid drugs, and postoperative complications are rare. Surgical treatment, therefore, plays an important role in the treatment of patients with hyperthyroidism. Those patients with sustained subclinical hypothyroidism after subtotal thyroidectomy should receive supplemental thyroid hormone.