Progesterone - Bioavailability

Bioavailability

Endogenous Progesterone

 90% - 98% of the body's Progesterone is bound to Cortisol Binding Globulin (CBG) for transportation around the bloodstream.  Approximately 2-10% of the body's Progesterone travels through the bloodstream in its "unbound" state.

 Eventually Progesterone is transported to the Liver where it is inactivated and metabolized:

 In the Liver, Progesterone is metabolized (by means of reduction, i.e. hydrogenation) to three groups of inactive substances:            Pregnanedione, Pregnanalones and Pregnanediol.

 These inactive metabolites are then bonded with Glucuronic Acid and excreted as water-soluble Glucuronides via (primarily) the Bile and (secondarily) the Urine.