FSH (Follicle-stimulating Hormone)

Follicle-stimulating hormone (FSH) is a hormone associated with reproduction and the development of eggs in women and sperm in men. This test measures FSH in the blood.

FSH is made by the pituitary gland, a small organ located in the center of the head behind the sinus cavity at the base of the brain. Control of FSH production is a complex system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries or testicles.

The hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary to release FSH and luteinizing hormone (LH), a closely-related hormone involved in reproduction.

Disorders affecting the hypothalamus, pituitary, and/or the ovaries or testicles can cause the production of too much or too little FSH, resulting in various conditions such as infertility, abnormal menstrual cycles, or early (precocious) or delayed puberty.