madman
Super Moderator
Background
Testosterone therapy is widely used for male hypogonadism but suppresses gonadotropins, reducing intratesticular testosterone and impairing spermatogenesis. These effects contribute to testicular atrophy, infertility, and increased risks such as erythrocytosis and estradiol elevation. Selective estrogen receptor modulators, including clomiphene and enclomiphene citrate, act through hypothalamic estrogen receptor blockade to stimulate endogenous LH and FSH secretion, restoring physiologic testosterone production. These agents may offer similar clinical benefit to testosterone therapy while preserving fertility and avoiding androgen-related adverse effects.
Objective
To systematically evaluate the comparative efficacy and safety of estrogen receptor modulators versus testosterone therapy in adult men with secondary hypogonadism.
Methods
Following PRISMA 2020 guidelines, PubMed, Embase, and Cochrane CENTRAL were searched through August 2025 for randomized controlled trials comparing clomiphene or enclomiphene citrate with any form of testosterone therapy. Primary outcomes included changes in serum total testosterone and validated symptom scores. Secondary outcomes included gonadotropins, estradiol, hematocrit, and semen parameters. Risk of bias was assessed using Cochrane RoB 2.
Results
Nine randomized trials (n = 932) met inclusion criteria. Both therapies increased serum testosterone into the eugonadal range (mean 450-650 ng/dL). Symptom improvement was comparable across energy, libido, sexual function, and quality-of-life domains. Estrogen receptor modulators consistently increased LH and FSH, while testosterone therapy uniformly suppressed both. Five trials reporting semen analysis demonstrated that estrogen receptor modulators preserved or improved sperm concentration and motility, whereas testosterone therapy reduced counts by 30-60% with frequent development of oligospermia or azoospermia. Hematocrit remained stable with estrogen receptor modulators but rose significantly in testosterone groups, with polycythemia occurring exclusively among testosterone-treated subjects. Estradiol levels increased with testosterone therapy but remained unchanged or decreased with estrogen receptor modulators. Overall study quality was high with low-to-moderate risk of bias.
Conclusions
Estrogen receptor modulators achieve testosterone normalization and symptom improvement equivalent to testosterone therapy while maintaining gonadotropin secretion, preserving spermatogenesis, and minimizing hematologic and estrogenic adverse effects. These findings support their role as a physiologic, fertility-preserving therapeutic option for men with secondary hypogonadism and highlight the need for longer-term trials evaluating metabolic, cardiovascular, and reproductive outcomes.
