Short-term triiodothyronine in prevention of temporary hypothyroidism after subtotal thyroidectomy for Graves' disease.

To determine whether short-term thyroid hormone replacement prevents or merely delays temporary hypothyroidism after surgery for Graves' disease, serum T3, thyroid-stimulating hormone, and T4 were measured every 2 months for 18 months in two groups of Graves' disease patients who had had subtotal thyroidectomy. Group I (18 patients) were given T3 20 microgram four times daily from surgery through the twelfth postoperative month. Group II (18 patients) received no treatment. Hypothyroidism occurred at some time during the 18-month period in 10 group-II patients, but was temporary in 7. Temporary hypothyroidism did not occur in group-I patients, whose mean T4 level rose to that in group II within 2 months of T3 withdrawal. Short-term T3 replacement after surgery for Graves' disease thus prevents (and does not simply delay) temporary postoperative hypothyroidism without increasing the frequency of permanent hypothyroidism.