Effect of vasectomy on the steroid profile of human seminal plasma

The effect of vasectomy on the steroid profile of seminal plasma was studied in 19 healthy men at 4-monthly intervals during a 2-year post-vasectomy period. The steroids analyzed by radioimmunoassays were: androstenedione (A), testosterone (T), dihydrotestosterone (DHT), oestradiol (E2) and the sulphoconjugated forms of pregnenolone (delta 5P-S), dehydroepiandrosterone (DHEA-S), testosterone (T-S), dihydrotestosterone (DHT-S), oestrone (E1-S) and oestradiol (E2-S). The quantitatively most important steroids present in the seminal plasma were DHEA-S, delta 5P-S and DHT-S. Vasectomy resulted in a significant but non-progressive reduction in DHT (40%) and T (23%) levels. The levels of E2, delta 5P-S and DHT-S also exhibited a smaller reduction following vasectomy. No significant changes were observed in the levels of the other steroids studied. The results are interpreted as suggesting that under normal conditions the bulk of the steroids present in the ejaculate is contributed by the accessory reproductive organs. In addition, a significant part of the DHT and T reach the ejaculate together with the sperm directly from the testis and/or epididymis. It is suggested that the normal steroid levels in seminal plasma established in this investigation could serve as reference values in the hormonal evaluation of male infertility.