T3 TOXICOSIS IN AN IODINE-DEFICIENT AREA

Abstract

In contrast to experience in New York where the frequency of triiodothyronine (T3) toxicosis among hyperthyroid patients is 4%, 56 (12·5%) of 449 patients in Chile, an area of iodine deficiency, were hyperthyroid by clinical and laboratory criteria but had normal serum-levels of protein-bound iodine (P.B.I.). 12 patients, investigated more fully, were unequivocally thyrotoxic on clinical grounds. P.B.I. and T4 levels were normal; serum-T3 levels were to raised between 264 and 840 ng. per 100 ml., with a mean of 480 ng. per 100 ml. Urinary iodide excretion was low in the two patients in whom it was assessed. These findings suggest that the frequency of T3 toxicosis is significantly higher in areas of iodine deficiency than in the United States. © 1972.