Ceiling effect of clomiphene citrate on the testosterone to estradiol ratio in eugonadal infertile men

INTRODUCTION: The testosterone to estradiol ratio (T/E2 ratio) reportedly exerts a stronger effect on semen quality and sexual desire than does testosterone alone. Clomiphene citrate is a selective estrogen receptor modulator that has long been used as an empirical treatment option in the management of idiopathic oligozoospermia. Clomiphene may change the hypothalamus–pituitary–gonad axis and result in the alteration of the T/E2 ratio. No reliable data are available regarding the change in the T/E2 ratio after clomiphene use in eugonadism. METHODS: This study included 24 male patients who were diagnosed with idiopathic infertility with eugonadism. They all received clomiphene citrate (25 mg/day) as empirical treatment. Blood tests for serum testosterone, estradiol, prolactin, luteinizing hormone, and follicle stimulating hormone were performed before and after 4 weeks of clomiphene use. Paired t-tests were used to evaluate the significance of the hormone level change. RESULTS: Overall, the patients’ T/E2 ratio did not increase significantly after clomiphene use. In the subgroup analysis, the T/E2 ratio of patients with a baseline ratio of <200 increased significantly after clomiphene use. CONCLUSIONS: Clomiphene citrate may significantly increase the T/E2 ratio in eugonadal men under the premise of its ceiling effect (T/E2 ratio < 200), providing practitioners with guidance on the use of clomiphene in this demographic.