https://www.fertstert.org/article/S0015-0282(14)02553-9/fulltext#sec2.1
https://www.maleinfertilityguide.com/hormone-testing-and-interpretation
Clomiphene citrate is a nonsteroidal estrogen agonist/antagonist existing as a racemic mixture of two isoforms (En-clomiphene and Zu-clomiphene) (32). This selective estrogen receptor modulator blocks the negative feedback of estrogen at the pituitary/hypothalamus level, thereby indirectly enhancing LH and FSH excretion from the anterior pituitary. Increased LH/FSH stimulation of the testes should increase both testosterone production and spermatogenesis, respectively. Studies have demonstrated that CC has resulted in moderate elevations in both LH/FSH and sperm concentration in patients with pregerminal hypofertility (10, 33) and in those with unexplained infertility (34, 35).
Not all patients will respond to CC stimulation. Patients starting with an elevated FSH level (35, 41) or lacking a post-treatment FSH surge (39) will not respond to CC.