Thyroid function after surgery for autonomous and non-autonomous nodular endemic goitre — effect of iodide-substitution

Publisher Website
Google Scholar
Abstract
The aim of this study was to evaluate the influence of postoperative iodide-substitution on the function of thyroid remnants of different quality and quantity in order to define the appropriate prophylaxis (iodide or thyroid hormone) to prevent recurrent goitre. In a prospective, randomized clinical trial, the following patients were examined:group I: simple, non-autonomous nodular goitre, bilateral thyroidectomy (n=40);group II: simple, non-autonomous nodular goitre, “selective” (unilateral) thyroidectomy (n=40);group III: autonomous nodular goitre, bilateral thyroidectomy (n=40);group IV: autonomous nodular goitre, “selective” (unilateral) thyroidectomy (n=35). The following parameters were measured 6 and 12 weeks postoperatively. Serum-total-T4, -T3,-TSH, TRH-test, 99mTc-Thyroid-Uptake (TcTU). Six weeks postoperatively the 4 groups were separately randomized into controls and treatment groups, who received 200 µg iodide/day orally. Six weeks postoperatively, patients in group I had lower T4 levels and both basal and stimulated TSH were higher than in the other groups, however no significant differences were observed in T3, T4/T3 ratio and TcTU.Twelve weeks postoperatively patients from groups I, II and III, who had been treated with iodide, had lower T3 and TcTU values but higher T4 and T4/T3 than the appropriate controls. Basal and stimulated TSH showed no differences between controls and iodide-treated patients in these groups. In group IV, T4and T3 showed a tendency to elevation (n.s.), and basal and stimulated TSH as well as TcTU were lower in patients with iodide. Iodide-substitution (200 µg/day) has no major influence on the pituitary-thyroid axis, except after “selective” surgery for autonomous nodular goitre (group IV). Generally, iodide treatment abolishes the symptoms of iodine-deficiency, improving the autoregulatory capacity of the thyroid remnant. It could replace thyroid hormone as a prophylaxis against recurrent goitre in the majority of patients after “selective” thyroid surgery.