LH (LUTEINIZING HORMONE)

LUTEINIZING HORMONE, LH, LUTROPIN

Luteinizing hormone (LH), also known as lutropin and sometimes lutrophin is a hormone produced by gonadotropic cells in the anterior pituitary gland. 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.

An LH test works closely with another hormone called follicle-stimulating hormone (FSH) to control sexual functions. So an FSH test is often done along with an LH test. These tests are used in different ways, depending on whether you are a woman, man, or child.

In women, these tests are most often used to:

• Help find the cause of infertility
• Find out when ovulation occurs, this is the time when you are most likely to get pregnant.
• Find the reason for irregular or stopped menstrual periods.
• Confirm the start of menopause, or perimenopause. Menopause is the time in a woman's life when her menstrual periods have stopped and she can't become pregnant anymore. It usually starts when a woman is around 50 years old. Perimenopause is the transition period before menopause. It can last for several years. LH testing may be done towards the end of this transition.

In men, these tests are most often used to:

• Help find the cause of infertility
• Find the reason for a low sperm count
• Find the reason for low sex drive

In children, these tests are most often used to help diagnose early or delayed puberty. Puberty is considered early if it starts before age 9 in girls and before age 10 in boys. Puberty is considered delayed if hasn't started by age 13 in girls and by age 14 in boys.