Excretion of Exogenous and Endogenous Estrogen in Bile of Dogs and Humans. ∗

Abstract

Discussion and Conclusions

Previous observations indicate that the bile is an important medium of excretion of exogenous estrogen (10,000-250,000 I.U. doses). The data reported here indicate that large amounts of endogenous as well as exogenous estrogen are excreted in the bile of human subjects and dogs, and may be present in the bile in com-paratively high concentration at a time when the concentration in the peripheral blood and urine is very low. The same is shown to be true following splenic implantation of a pellet of alpha-estradiol. The possibility of the existence of an enterohepatic circulation of estrogen is supported further by the demon-stration (1) of the presence of large amounts of estrogen in the mesenteric-vein blood (dog) after instillation of alpha-estradiol into an isolated intestinal loop and (2) of the excretion of estrogen in the bile of dogs following instillation of estrogen into the duodenum.