LH is a hormone that is produced in the pituitary gland in both men and women. In women, LH is an important part of the menstrual cycle. It works in conjunction with follicle-stimulating hormone (FSH), also made in the pituitary gland. FSH stimulates the ovarian follicle causing an egg to grow. It also triggers the production of estrogen in the follicle.

The rise in estrogen tells the pituitary gland to stop producing FSH and to start making more LH. The shift to LH causes the egg to be released from the ovary, a process called ovulation. In the empty follicle, cells proliferate, turning it into a corpus luteum. This structure releases progesterone, a hormone necessary to maintain pregnancy. If pregnancy does not occur, levels of progesterone drop off and the cycle begins again.

In men, LH is also produced in the pituitary gland. LH binds to receptors in certain cells in the testes called Leydig cells. This leads to the release of testosterone, a hormone that is necessary for producing sperm cells.

What Is Luteinizing Hormone?