Effect of aromatase inhibitor, letrozole on semen parameters in eugonadotropic hypoandrogenic men with oligozoospermia

Background: Some men with severely defective sperm production commonly have excess aromatase activity, reflected by low serum testosterone and relatively elevated estradiol levels. Elevated levels of estrogen lead to feedback inhibition of the hypothalamic -pituitary-gonadal axis, and the end result is a decrease in LH necessary for the production of testosterone, and FSH to optimize sperm production. The aim of this study was to evaluate the effect of aromatase inhibitor, letrozole on the semen parameters of infertile male having oligozoospermia, low serum testosterone level and testosterone to estradiol ratio <10.Methods: This Prospective study was conducted in the Department of Reproductive Endocrinology and Infertility at Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh during the period from May 2019 to April 2020. The sample size was 30 subfertile men with oligozoospermia (≤ 10 million/ml), low serum testosterone level (<300 ng/dl) and low testosterone to estradiol ratio (<10). All patients were treated with letrozole 2.5 mg daily for 4 months. At the end of the 4 months the semen analysis was performed. Statistical analysis was carried out by using IBM Statistical Package for Social Sciences version 25 for windows (SPSS version 25.0).Results: The sperm concentration, sperm motility and total motile sperm count significantly increased after letrozole treatment. The side effects were mild and well tolerated.Conclusions: This study suggests that some men with oligozoospermia, low serum testosterone levels and normal gonadotropin concentration may have a treatable endocrinopathy. Letrozole may be used to improve sperm parameters in infertile men with low serum testosterone to estradiol ratio