When only mg of progesterone was applied topically, the plasma level rose 39 percent, whereas saliva level rose 5-fold. This indicates that only a small portion of the added progesterone entered the plasma, whereas the saliva clearly showed a hefty increase of bioavailable progesterone. When an 88-fold larger dose was applied topically, the plasma level rose only -fold while the simultaneous saliva level rose 57-fold. This indicates that only the saliva reflected the great increase in absorbed bioavailable progesterone. The progesterone found in the saliva obviously was blood-borne, but it should be clear that the portion of the blood carrying the progesterone was not the plasma (serum) but, rather, was via red blood cells.