Plasma levels of steroid glucuronides in prepubertal, adult and elderly men.

The present study has been designed to measure the levels of C-19 steroids and their glucuronide derivatives (G) in the plasma of males at three different ages: (1) 4-7 years old, (2) 20-35 years old and (3) 55-70 years old. In 4-7 years old, the plasma levels of the free and conjugated C-19 steroids were almost undetectable. From the data obtained in both groups of adult men, it appeared that except for androsterone, the levels of all free C-19 steroids were diminished by 10-70% during aging. In adult men, androsterone-G was the predominant C-19 steroid-G in plasma. The levels of androsterone-G, in the group of 20-35 years old, exceed by 3 and 20-fold the levels of androstane-3 alpha, 17 beta-diol-G and androstane-3 beta, 17 beta-diol-G, respectively. During aging, while the levels of androsterone-G and androstane-3 beta, 17 beta-diol-G were decreased or in the case of androstane-3 alpha,17 beta-diol-G remained unchanged, testosterone-G and dihydrotestosterone-G levels were markedly increased, suggesting a modification in the action of glucuronyl transferase during aging.