Absorption of Thyroxine from the Small Intestine of Rats

Abstract
During 1 hr 20-50 % of a tracer dose of radiothyroxine was absorbed in vivo from washed intestinal loops of rats. The absorption was much slower during the succeeding 5 hr. Studies by dialysis, cellulose acetate electrophoresis and an anion exchange resin suggested that protein, possibly plasma albumin, secreted into the intestinal lumen reduced the absorption of thyroxine from the washed intestinal loop. (Endocrinology74: 694, 1964)