Human Chorionic Gonadotropin β-Subunit in Human Semen

Abstract

The level of human seminal chorionic gonadotropin beta-subunit (hCG beta) was determined by radioimmunoassay (RIA). The mean hCG beta level in 34 normal men was 3.7 +/- 1.6 ng/ml, which was much higher than that in serum. The mean hCG beta level for 20 patients with mild oligozoospermia (20-39 x 10(6) sperm/ml) was 2.5 +/- 0.8 ng/ml, that for 34 patients with severe oligozoospermia (1-19 x 10(6) sperm/ml) was 1.7 +/- 0.5 ng/ml, and that for 21 azoospermia was 1.5 +/- 0.6 ng/ml. Thus, the decrease of sperm count was correlated with the decrease of hCG beta. In 17 cases to which testicular biopsy was applied together with sperm counting, the seminal hCG beta level was found to positively correlate with the germinal cell index (the ratio germinal cell count/Sertoli cell count) and with the testicular volume. The level of seminal hCG beta was also found to correlate negatively with the levels of seminal LH and FSH and positively with the level of seminal testosterone. These findings suggest that the production of seminal hCG beta is a process of spermatogenesis and closely related to spermatogenesis. The level of hCG beta in serum was too low to detect, and no relation to that in seminal plasma could be investigated. However, in 6 cases with testicular tumor, the hCG beta level in serum was high, whereas that in seminal plasma was rather low probably because of unilateral secretion. Enhanced production of hCG beta by tumor tissues and the destruction of the blood-testis barrier by proliferation of tumor cells seemed to be one of the causes of this high hCG beta level in serum. The hCG beta levels in 13 vasectomized seminal plasma and the prostatic fluid samples collected from 3 normal men were 1.5 ng/ml, which was similar to those in azoospermic patients. These findings suggest that the seminal hCG beta level consists of the hCG beta secreted by the testis and about 1.5 ng/ml of hCG beta from the prostate. Based on these results, seminal hCG beta is thought to be secreted by the prostate and the process of spermatogenesis and the value of seminal hCG beta may serve as an effective index for the testicular function.