Preliminary study of letrozole use for improving spermatogenesis in non-obstructive azoospermia patients with normal serum FSH.

We investigated whether letrozole (2.5 mg day(-1)) improves sperm count in non-obstructive azoospermia (NOA) patients. Four men were included in this study, and they had folliculo-stimulating hormone and other hormone levels within the normal range and no varicoceles or chromosomal aberrations. These four patients were administered letrozole for 3 months. Sperm count, testicular volume, gonadotropin, testosterone (T) and estradiol (E2) blood levels were assessed before, during and 1 week after the suspension of treatment. All patients showed spermatozoa in their ejaculate, increased gonadotropin and T levels and lower E2 levels (P<0.05 in all cases), when letrozole was administered. This suggests that letrozole treatment might improve sperm count in an NOA sub-population; however, more studies, including the proper controls, are needed to confirm its efficacy.