The acute thyroidal response to iodixed oil in severe endemic goiter.

The acute changes in serum thyrotropin (TSH) triiodothyronine (T3) and thyroxine (T4), were measured in 14 subjects, 4 to 10 (mean = 6) days following intramuscular iodized oil injection. In 8 subjects with small or absent goiter there was a significant fall in T3 and a rise in TSH concentrations, suggesting an acute inhibitory effect of the iodine. In 6 subjects with large multinodular goiters there was a marked rise in both T3 and T4, and reduction in the elevated basal TSH. Biochemical hyperthyroidism occurred in 3 of these subjects. The acute thyroid hormone response to iodized oil, whether inhibitory or stimulatory in a particular subject, depends both on goiter size and on the serum concentration of TSH.