Follicle Stimulating Hormone (FSH)

FSH is a hormone made by the pituitary gland in the brain that plays an important role in reproduction. In women, it helps control the menstrual cycle and egg development; in men, it supports sperm production. When FSH is higher than normal, it may mean the ovaries or testes are not responding as expected, which can affect fertility. When FSH is lower than normal, it may suggest the brain is not sending the right signals to the reproductive organs. Your doctor will look at FSH alongside other hormones and your overall health to understand what the result means for you.

When elevated: Elevated FSH suggests primary gonadal insufficiency, diminished ovarian reserve, premature ovarian insufficiency, or menopause in women. In men, high FSH may indicate primary testicular failure or Klinefelter syndrome. Persistently elevated FSH warrants further evaluation of gonadal function and fertility potential. When low: Low FSH levels suggest hypothalamic or pituitary dysfunction, including hypogonadotropic hypogonadism, hyperprolactinemia, or suppression from exogenous hormones. Low FSH may also be seen in conditions of chronic illness, significant weight loss, or excessive exercise that disrupt the HPG axis. This pattern requires evaluation of the entire pituitary-gonadal axis.

FSH is less directly relevant to athletic performance than testosterone or cortisol, but it reflects reproductive and hormonal health—both important for sustained training capacity and recovery. Chronically elevated training stress, low energy availability, or overtraining can suppress the HPG axis and lower FSH, signaling potential reproductive strain; monitoring FSH alongside other hormones helps athletes maintain hormonal balance for long-term health and fertility.