AGE DEPENDENCE OF TESTOSTERONE PRECURSORS IN PLASMA OF NORMAL ADULT MALES

ABSTRACT Radioimmunoassays for the measurement of pregnenolone1), 17α-hydroxy-progesterone, androstenedione, dehydroepiandrosterone (DHEA) and androstenediol (5-androstene-3β,17β-diol) have been developed. In addition the reliability criteria of these methods have been established. Age dependence of testosterone precursors in plasma was studied in 80 normal males aged 19 to 93 years. When a young to middle aged group (19–54 years) was compared with an old age group (67–93 years) a highly significant (P < 0.001) decrease was observed for all the precursors studied: DHEA −68.1%, pregnenolone −60.3%, androstenediol −53.8%, 17α-hydroxyprogesterone −47.5% and androstenedione −39.2%. Nine old patients (60–81 years) with prostatic carcinoma were studied before and 1 week after therapeutic castration. The results indicate that approximately 73% of the peripheral 17α-hydroxyprogesterone, 55% of the androstenediol, 52 % of the pregnenolone, 31 % of the androstenedione and 27 % of the DHEA are of testicular origin in old men with prostatic cancer. HCG-stimulation tests were performed in 12 young (21–30 years) and 12 old (69–83 years) men. There was no significant increase in pregnenolone and in DHEA in both age groups. The relative increase of 17α-hydroxyprogesterone, androstenedione and androstenediol did not differ between young and old men. The absolute increase of androstenedione and androstenediol was twice as high in the young men.