Nonimmunogenic hyperthyroidism: cumulative hypothyroidism incidence after radioiodine and surgical treatment.

During 1977, 246 hyperthyroid patients were seen in our departments, 140 (57%) with nonimmunogenic hyperthyroidism (NIH)--101 with a toxic adenoma (TA) and 39 with multifocal functional autonomy (MFA). All patients but one could be followed over 9 yr, 101 after 131I treatment (RIT), another 29 after surgery (S). Ten patients were left untreated. Thirty-four treated (24%) patients died, none as a result of thyroid or post-treatment complications. There was no hyperthyroidism later than 9 mo after therapy. Only 1% (RIT) and 24% (S) were hypothyroid 1 yr after treatment. But 19% of all treated NIH patients were hypothyroid after 9 yr or at the time of their death, 12% after RIT and 41% after S. The cumulative hypothyroidism incidences 1.4%/yr for RIT and 2.2%/yr for S, were not significantly different. Out of the five survivers without RIT or S, two TA patients were hypothyroid. The effect of RIT on goiter related loco-regional complications was not worse than after S. We conclude that RIT is the treatment for NIH, leaving surgery for exceptional cases.