This test measures the level of follicle-stimulating hormone (FSH) in your blood. FSH is made by your pituitary gland, a small gland located underneath the brain. FSH plays an important role in sexual development and functioning.

In women, FSH helps control the menstrual cycle and stimulates the growth of eggs in the ovaries. FSH levels in women change throughout the menstrual cycle, with the highest levels happening just before an egg is released by the ovary. This is known as ovulation.

In men, FSH helps control the production of sperm. Normally, FSH levels in men do not change very much.

In children, FSH levels are usually low until puberty, when levels begin to rise. In girls, it helps signal the ovaries to make estrogen.

In boys, it helps signal the testes to make testosterone.

Too much or too little FSH can cause a variety of problems, including infertility (the inability to get pregnant), menstrual difficulties in women, low sex drive in men, and early or delayed puberty in children.

This test measures the level of luteinizing hormone (LH) in your blood. LH is made by your pituitary gland, a small gland located underneath the brain. LH plays an important role in sexual development and functioning.

In women, LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is known as ovulation. LH levels quickly rise just before ovulation.

In men, LH causes the testicles to make testosterone, which is important for producing sperm. Normally, LH levels in men do not change very much.

In children, LH levels are usually low in early childhood, and begin to rise a couple of years before the start of puberty. In girls, LH helps signal the ovaries to make estrogen. In boys, it helps signal the testes to make testosterone.

Too much or too little LH can cause a variety of problems, including infertility (the inability to get pregnant), menstrual difficulties in women, low sex drive in men, and early or delayed puberty in children.

A prolactin (PRL) test measures the level of prolactin in the blood. Prolactin is a hormone made by the pituitary gland, a small gland at the base of the brain. Prolactin causes the breasts to grow and make milk during pregnancy and after birth. Prolactin levels are normally high for pregnant women and new mothers. Levels are normally low for nonpregnant women and for men.

If prolactin levels are higher than normal, it often means there is a type of tumor of the pituitary gland, known as a prolactinoma. This tumor makes the gland produce too much prolactin. Excess prolactin can cause the production of breast milk in men and in women who are not pregnant or breastfeeding. In women, too much prolactin can also cause menstrual problems and infertility (the inability to get pregnant). In men, it can lead to lower sex drive and erectile dysfunction (ED). Also known as impotence, ED is the inability to get or maintain an erection.