Remnant function after subtotal thyroidectomy for Graves' disease.

Although it has been thought that future thyroid function after subtotal thyroidectomy for Graves' disease was intimately related to the mass of the thyroid remnant, long-term functional results have not been clearly established. These questions were examined in a retrospective study of 86 surgical cases with histologically confirmed Graves' disease. Operation resulted in euthyroidism in 76% of cases. Recurrent thyrotoxicosis appeared in 8%. Hypothyroidism developed in 14 patients (16%), all with estimated remnant weights of less than 8 gm. In each case, hypothyroidism was diagnosed within the first postoperative year. The capability for early diagnosis of hypothyroidism, however, is a significant advantage of surgical treatment. Within the range of estimated remnant weights, a significant and negative correlation was found between remnant size and the subsequent development of hypothyroidism, but neither euthyroidism nor recurrence of thyrotoxicosis could be correlated with remnant size. In the individual patient, therefore, estimated remnant size is of limited value in predicting future thyroid function.