Dependence of ratio of radioiodide concentrations in thyroid gland and serum on serum iodide concentration: without propylthiouracil.

Abstract

THE ratio of the thyroid radioiodide concentration to the serum radioiodide concentration (T/S ratio) was less when organic binding of iodine by the thyroid gland was permitted, than when binding was blocked by propylthiouracil (Wollman and Scow, 1953). Since a sufficiently high concentration of serum iodide is known to block binding of iodine in the rat (Wolff and Chaikoff, 1948), it might be expected to block thyroid binding of iodide in the mouse and thereby elevate the T/S ratio in the mouse. This paper presents data describing the dependence of the T/S ratio on the serum iodide concentration in mice. The preceding paper (Wollman and Scow, 1954) described a similar study with the exception that the mice were given a single dose of propylthiouracil to block binding. A comparison is made of the T/S ratio when binding is blocked by iodide with that when binding is blocked by both prop3dthiouracil and iodide. METHODS AND MATERIALS Male C3H mice, four months of age, were used.