Clomiphene or tamoxifen for idiopathic oligo/asthenospermia

Oligo-astheno-teratospermia (sperm of low concentration, reduced motility and increased abnormal morphology) of unknown cause is common and the need for treatment is felt by patients and doctors alike. As a result, a variety of empirical, non-specific treatments have been used in an attempt to improve semen characteristics and fertility. The administration of anti-oestrogens is a common treatment because anti oestrogens interfere with the normal negative feedback of sex steroids at hypothalamic and pituitary levels in order to increase endogenous gonadotropin-releasing hormone secretion from the hypothalamus and FSH and LH secretion directly from the pituitary. In turn, FSH and LH stimulate Leydig cells in the testes, and this has been claimed to lead to increased local testosterone production, thereby boosting spermatogenesis with a possible improvement in fertility. There may also be a direct effect of anti-oestrogens on testicular spermatogenesis or steroidogenesis. This review considers the available evidence of the effect of both Clomiphene citrate and tamoxifen, both of which have a predominant anti-oestrogenic effect, for idiopathic oligo and/or asthenospermia.

The objective was to assess the effects of treating subfertile men with anti-oestrogens (clomiphene or tamoxifen) on pregnancy rates among couples where subfertility has been attributed to idiopathic oligo- and/or asthenospermia.

The Cochrane Subfertility Review Group specialised register of controlled trials was searched".

Randomised trials of anti-oestrogen therapy for 3 months or more compared to placebo or no placebo for subfertile males among couples where subfertility is attributed to male factor.

Data were extracted independently by two reviewers. Any differences were resolved with a third reviewer.

Ten studies involving 738 men were included. Five of the trials did not specify method of randomisation. Anti-oestrogens had a positive effect on endocrinal outcomes, such as serum testosterone levels. In trials with secure randomisation there was no difference in the pregnancy rate between the anti-oestrogen groups and the control groups (odds ratio 1.26, 95% confidence interval 0.99 to 1.56). The overall pregnancy rate for these five trials was 15.4% compared to the spontaneous rate of 12.5% in the control groups. These odds increased to 1.56 (95% confidence interval 0.99 to 2.19) when all 10 trials were included, but this result is likely to be artificially inflated.

Anti-oestrogens appear to have a beneficial effect on endocrinal outcomes, but there is not enough evidence to evaluate the use of anti-oestrogens for increasing the fertility of males with idiopathic oligo-asthenospermia.