What is follicle stimulating hormone (FSH)?
Follicle stimulating hormone (FSH) is a pituitary gland hormone that directly controls sperm production in the testes and is routinely measured in TRT baseline screening.
FSH, produced by the anterior pituitary gland, is the primary hormone responsible for stimulating spermatogenesis (sperm production) in the male testes. It works alongside luteinizing hormone (LH) to maintain normal testosterone levels and reproductive function. In men, FSH acts on Sertoli cells within the seminiferous tubules, which are essential for developing and maturing sperm.
Because testosterone replacement therapy can suppress natural FSH production through negative feedback on the pituitary gland, clinics in Miami and elsewhere measure baseline FSH levels before initiating treatment. Low or suppressed FSH during TRT can lead to reduced sperm counts and temporary infertility, making it an important marker for men concerned about fertility. TRT providers use FSH testing as part of comprehensive hormone panel screening to help patients understand potential reproductive impacts and explore options like human chorionic gonadotropin (hCG) or other adjunct therapies to preserve fertility during hormone replacement.
Normal FSH levels in adult men typically range from 1.7 to 8.6 mIU/mL, though reference ranges vary by laboratory. Elevated baseline FSH may indicate existing testicular dysfunction, while suppressed FSH during active TRT is expected but reversible in most cases after treatment is discontinued.