A comparative study of avian and rat patterns in thyroid function—I. intrathyroidal iodine metabolism

Abstract

1. Ducks, pigeons or quail, fed an iodine adequate diet (IAD) show a very small T 3/T 4 ratio compared to the rat (0·03 vs 0·14). 2. The stable iodine content of the duck thyroid is four to five times greater than in the rat (4·70 ± 0·30 μg/mg thyroid vs 0·86 ± 0·08 μg/mg) corresping to an elevated 131I retention after a tracer dose injection. 3. Equilibration between pre-existing 127I and newly injected 131I, occurs after 48 hr in the rat and 96 hr in the duck. 4. Iodine deficiency leads to equilibrium between % of iodine in MIT and DIT in the rat thyroid, while % in MIT remains smaller than in DIT in the duck thyroid.