Effect of preoperative iodine in patients with Graves' disease controlled with antithyroid drugs and thyroxine.

Thirty-four patients with Graves' disease, first rendered euthyroid with antithyroid drugs (ATD) then given supplementary thyroxine (T4), were randomly allocated to three treatment groups. In Group I ATD and T4 were stopped 10 days before partial thyroidectomy and the patients were treated with Lugol's iodine alone. In Group II the patients were treated up to the time of operation with ATD and T4 alone. In Group III ATD and T4 were continued until the day of operation, but the patients also received 10 days' treatment with Lugol's iodine. Analysis of the results showed that pre-operative iodine therapy in patients with Graves' disease, already rendered euthyroid with ATD and T4, made no difference to the vascularity of the gland, operative blood loss or thyroid follicular size. Over a third of patients in Group I, treated with Lugol's iodine alone for 10 days pre-operatively, had subnormal levels of thyroid hormones at the time of operation and this was also the Group in which the complications of partial thyroidectomy tended to occur. It is concluded that the addition of iodine preoperatively is unnecessary in the patient who is already euthyroid on ATD and T4.