Vasectomy: a long-term study of its effects on testicular endocrine function in man

Possible biological mechanisms for a relationship between vasectomy and prostatic cancer

Four hypotheses have been reviewed, each of which might serve as a hypothetical biological explanation for a relationship between vasectomy and prostate cancer. The endocrine hypothesis is the only one of these with any firm data to support it, although the majority of the available data does not lend credibility to that theory. The other hypotheses are purely speculative with no hard data to support them. In conclusion, it seems highly unlikely, but not impossible, that there is a biological mechanism supporting a relationship between vasectomy and prostate cancer.

The effect of vasectomy on the production of plasma luteinizing hormone and follicle stimulating hormone in man

A prospective study of plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) in 51 men before vasectomy and 10 days and 3 months after vasectomy revealed a trend to rise in LH 10 days after vasectomy normalizing after 3 months. The literature concerning alterations in LH and FSH after vasectomy is reviewed and different theories are discussed.

Detection of testicular endocrine abnormalities and their correlation with serum antisperm antibodies in men following vasectomy

We measured the serum gonadotropin response to gonadotropin-releasing hormone in 25 men who underwent vasectomy 2 to 64 months before the study. Ten age-matched fertile men were used as controls. Baseline serum follicle-stimulating hormone, luteinizing hormone and testosterone levels were not significantly different between vasectomized men and controls. However, mean serum follicle-stimulating and luteinizing hormone responses to an intravenous bolus injection of 100 mcg. gonadotropin-releasing hormone were significantly greater in the vasectomy group (p equals 0.008 and 0.003, respectively). There was no correlation between these responses and the interval after vasectomy. Serum antisperm antibodies were present in 13 vasectomized men (52 per cent) using enzyme-linked immunosorbent assay and microagglutination techniques. A significant correlation (p equals 0.003) was found between the presence of serum antisperm antibodies and a normal follicle-stimulating hormone response to gonadotropin-releasing hormone stimulation. Of 13 patients with demonstrable antisperm antibody titers 9 (69 per cent) had normal follicle-stimulating hormone responses, compared to only 1 of 12 (8 per cent) without identifiable antisperm antibody titers. Our data suggest that certain men following vasectomy have abnormalities in seminiferous tubule and Leydig cell functions of the testes. These abnormalities are unrelated to the interval after vasectomy and are not identifiable with routine static hormonal measurements. In addition, serum antisperm antibodies are most likely to be present in men who demonstrate normal seminiferous tubular activity after vasectomy.

Lack of effect of vasectomy on peripheral gonadotrophin and steroid levels

In order to re-assess the possible hormonal consequences of male sterilization, the peripheral plasma levels of lutropin (LH) follitropin (FSH), and dihydrotestosterone sulphate (DHT-S) were measured in a group of 20 healthy men at weekly intervals in the month before and at bimonthly intervals up to 2 years after vasectomy. In addition, the levels of 14 steroids of gonadal and/or adrenal origin were measured before, and then every second month (12 subjects) or every sixth month (8 subjects) following vasectomy. No significant alterations were observed in the levels of any of the hormones studied. The results are interpreted as indicating that in the first 2 years following vasectomy in men there is no consistent or progressive change in the peripheral plasma levels of gonadotrophins or in a variety of steroids of testicular and/or adrenocortical origin.

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.

The hormonal and immunological status of vasectomised men

The concentration of FSH, LH, testosterone and sperm agglutinating and cytotoxic antibodies have been determined in 87 men at varying time intervals after vasectomy. The results indicated that vasectomy is not associated with statistically significant changes in any of these parameters. Furthermore, no correlation existed between the development of sperm antibodies and the peripheral endocrine status of an individual.

The endocrine effects of vasectomy: a prospective five-year study

A prospective study of plasma luteinizing hormone (LH) and testosterone in 54 men for 5 years following vasectomy revealed no significant continuing alteration in either testosterone or LH. Plasma LH levels 1 year after operation were higher than preoperative levels but did not increase further. Stimulation studies (4 years postvasectomy) using human chorionic gonadotropin confirmed acceptable Leydig cell functional reserve.

Evaluation of proteohormon concentrations in serum and seminal fluid and its relationship with sperm count

The measurement of FSH, LH, and PRL in serum and seminal fluid of 105 men attending a male infertility clinic and 21 men of proven fertility (controls) did not reveal an interrelationship between the spermatozoal count and the level of the proteo-hormones in both biological fluid except for FSH, which was significantly higher in the serum of men with low as compared to normal sperm count (p less than 0.01). FSH in seminal fluid was significantly lower (p less than 0.01), and LH-like activity significantly higher (p less than 0.01) than in serum, while there was no difference between the respective levels of PRL. These results could be confirmed in 4 patients with azoospermia due to occlusive disease, and in 1 out of 2 vasectomized men. It was demonstrated for the first time that the higher concentration of "LH" in seminal fluid as compared to serum was due to the presence of HCG-beta or a HCG-like material cross-reacting with the antiserum against LH.