Five-year follow-up of a randomized clinical trial of unilateral thyroid lobectomy with or without postoperative levothyroxine treatment.

Background: The aim of this study was to compare the prevalence of recurrent nodular goiter in the contralateral thyroid lobe among patients after unilateral thyroid lobectomy for unilateral multinodular goiter (MNG) receiving versus not receiving postoperative prophylactic levothyroxine (LT4) treatment.
Methods: From January 2000 through December 2003, 150 consenting patients underwent a unilateral thyroid lobectomy for unilateral MNG at our institution. They were randomized to two groups with 75 patients in each group. Patients in group A received prophylactic LT4 treatment postoperatively (dose range 75-125 microg/day to maintain thyroid-stimulating hormone values below 1.0 mU/L), whereas patients in group B received no postoperative LT4 treatment. All the patients underwent ultrasonographic, cytologic, and biochemical follow-up for at least 60 months postoperatively. The primary outcome was the prevalence of recurrent goiter in the contralateral thyroid lobe. The secondary outcome was the reoperation rate for recurrent goiter. The outcomes were stratified according to individual iodine metabolism status assessed by urinary iodine excretion.
Results: During the 5-year follow-up, among patients receiving vs. not receiving LT4, recurrent goiter within the contralateral thyroid lobe was found in 1.4% vs. 16.7% of patients, respectively (p = 0.001). Moreover, 1.4% vs. 8.3%, respectively, of patients receiving vs. not receiving LT4 required contralateral thyroid lobe surgery (p = 0.05). LT4 decreased the recurrence rate among iodine-deficient patients (3.4% vs. 36%, respectively; p = 0.002) but not among iodine-sufficient patients (0% vs. 6.4%, respectively; p = 0.09).
Conclusions: Prophylactic LT4 treatment significantly decreased the recurrence rate of nodular goiter in the contralateral thyroid lobe and the need for completion thyroidectomy, mostly among patients with iodine deficiency.