The importance of elevated TSH in serum after subtotal thyroidectomy for hyperthyroidism. A five-year follow-up study

68 patients operated on for hyperthyroidism were observed regularly for 5 years after operation as regards the concentration of TSH in serum and the incidence of hypothyroidism and recurrent hyperthyroidism. 20 patients had elevated TSH 6 weeks after operation. 5 years later 9 of them had developed hypothyroidism, 6 had elevated TSH without clinical symptoms of hypothyroidism, while 5 were normal in all measured thyroid variables. 48 patients had normal TSH 6 weeks after operation. 5 years later 5 of them had developed a recurrence of hyperthyroidism, 4 had elevated TSH with no clinical symptoms of hypothyroidism, while the remaining 39 patients were euthyroid with normal thyroid variables. A scheme for follow-up of patients operated on for hyperthyroidism is proposed, with close follow-up of patients with elevated TSH soon after operation.