How are Testosteron and fertility related?

Testosterone is essential for male fertility, primarily by driving spermatogenesis. Low testosterone levels can reduce sperm count and quality, but the relationship is nuanced: exogenous testosterone (e.g., anabolic steroids or testosterone replacement therapy) suppresses the hypothalamic-pituitary-gonadal axis, leading to reduced intratesticular testosterone and impaired sperm production. Thus, testosterone therapy can actually cause infertility. Fertility requires a delicate hormonal balance involving FSH and LH. A simple blood testosterone test is insufficient; semen analysis is the gold standard. For men planning conception, alternatives like hCG or clomiphene citrate may preserve fertility. Evidence is strong from clinical studies, but individual variation (genetics, lifestyle, age) matters. DNA tests for testosterone-related SNPs (e.g., FUT2) have limited clinical utility for fertility prediction. Always consult a reproductive specialist.