Testicular function in potential sperm donors: normal ranges and the effects of smoking and varicocele

Open Access
Publisher Website
Google Scholar
Abstract
Testicular exocrine (semen analysis) and endocrine (plasma LH, FSH, prolactin and testosterone) function was assessed in 119 consecutive healthy men presenting for screening as potential sperm donors. Since these volunteers were unbiased with respect to their fertility status, this sample of the general male population was suitable to determine normal ranges and the influence of a variety of physical (height, weight, standardized body weight, varicocele) and demographic (age, marital and fertility status, tobacco and alcohol consumption) factors on normal human testicular endocrine and exocrine function, without the confounding effects of bias in selection of subjects. The statistical distribution of all seminal parameters was non-gaussian, but cube-root transformation of the data normalized the distribution, allowing for parametric statistical analysis. The median (and 95% confidence limits) for the various semen parameters was 73.0 (10.6–235.3) million sperm per ml; 189.0 (12.6–868) million sperm per ejaculate; 50.4 (5.9–181.9) million motile sperm per ml; 133.0 (6.9–661.7) million motile sperm per ejaculate; 54.0 (7.0–172.9) million morphologically normal sperm per ml and 138.5 (7.5–672) million morphologically normal sperm per ejaculate. Testicular volume was correlated positively with measures of physique such as standardized body weight (r = 0.25, P < 0.01) and body surface area (r = 0.30, P < 0.002), and negatively with plasma levels of FSH (r = -0.31), P < 0.002) but not LH. Sperm output was positively correlated with testicular volume (r = 0.28, P < 0.005) and negatively correlated with plasma FSH (r = -0.31, P < 0.002) and plasma LH (r = -0.31, P < 0.002). Smoking was associated wih a highly significant reduction in sperm output and motility. Men with varicocele (25%) were significantly taller, had slightly lower haemoglobin levels and moderate left (but not right) testicular atrophy, but neither seminal nor hormonal parameters were different from men without varicocele. There was no difference in any markers of human testicular function between men according to marital or fertility status, grades of moderate alcohol consumption or the presence of low titres of sperm antibodies.