Controlled by hormones produced in the pituitary gland, hypothalamus, and ovaries or testes. FSH regulates various hormonal functions in men and women, where insufficient levels in either sex can give rise to infertility. It also controls oestrogen secretion, where it rises during the first half of the menstrual cycle, and decreases after ovulation. This test helps to identify irregular menstrual periods, as well as women who are struggling to get pregnant, going through menopause, or have symptoms of ovarian disease.
In men, the hormones testosterone and inhibin control FSH production. It stimulates sperm production and testicular growth and can help to identify symptoms of testicular disease.