"On average, the men had been infertile for nearly three years. The men received a 2.5-milligram letrozole pill every week. Their follow-up ranged from two to 21 months."
Letrozole Shows Promise for Treating Infertility in Obese Men <<<<that'll get you an article.*
"After initiating low-dose letrozole, estradiol decreased from 119.5 nmol/L to 72.2 nmol/L; mean FSH increased from 4.4 IU/L to 8.0 IU/L; mean LH increased from 4.4 IU/L to 6.6 IU/L; and mean total testosterone increased from 7.4 nmol/L to 21.1 nmol/L. Additionally, mean sperm count increased from 14.8 x 109/L to 64.5 x 109/L."
While no estrogen was included estrogen is needed to male sperm. The studies participants couldn't have had crashed estrogen.
""Role of estrogens in spermatogenesis.Review article
Carreau S, et al. Front Biosci (Elite Ed). 2012.
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Aromatase converts irreversibly androgens into estrogens and is present in the endoplasmic reticulum of various cells of mammalian testes ; at least in rodents, all testicular cells except peritubular cells express aromatase. In testis, high affinity estrogen receptors, ERalpha and/or ERbeta, together with a membrane rapid effect recently described, mediate the effects of estrogens. From the experimental models, in vitro studies and data collected in patients, it is now demonstrated that estrogens play an important role in the testis of vertebrates. At least it is supported by the widespread distribution of estrogen receptors in the testicular cells and the simultaneous presence of a biologically active aromatase in all germ cells (especially in meiotic and post-meiotic stages). Thus the role of estrogens (intracrine, autocrine and / or paracrine) in spermatogenesis (proliferation, apoptosis, survival and maturation) and more generally, in male reproduction is now evidenced, and much more complex than previously predicted."