Luteinizing Hormone (LH) Levels Test

This test measures the level of luteinizing hormone (LH). A hormone is a chemical messenger in your bloodstream that controls the actions of certain cells or organs. LH is usually measured in a sample of your blood.

But in certain cases, it may be measured in urine (pee). LH plays an important role in sexual development in children and fertility in adults: In women who menstruate (have periods), LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary.

This is called ovulation. LH levels quickly rise just before ovulation. If you're trying to have a baby, this monthly increase in LH tells you when you're most likely to become pregnant.; In men, LH causes the testicles to make the hormone testosterone, which is important for making sperm.

Normally, LH levels in men do not change very much.; In children, LH levels are normally low in early childhood. They begin to rise slowly in the years before puberty, usually between ages six and eight. As puberty begins LH continues to rise along with levels of other hormones.

The increase in all of these hormones triggers the physical changes of puberty: In girls, LH helps signal the ovaries to make the hormone estrogen. Estrogen is involved in the growth of breasts, body hair, and the start of menstruation.; In boys, LH helps signal the testicles to make testosterone. Testosterone is involved in the growth of facial and body hair, changes in a boy's voice, and sperm production.; ; LH levels are controlled by a complex system of hormones made in different parts of your body.

Abnormal levels of LH may be a sign of a problem with any of these parts. They include your: Pituitary gland, a small gland at the base of your brain. It makes LH.; Hypothalamus, a part of your brain.

It makes hormones that tell your pituitary gland how much LH to make.; Reproductive glands, your ovaries or testicles. The amount of sex hormones they make let your hypothalamus and pituitary gland know when to start and stop making LH.;

Why this test is done

For women:

You may need this test if:

• You've been unable to get pregnant after 12 months of trying.
• Your menstrual periods aren't regular or have stopped.

If you're age 45 or older, testing usually isn't needed. That's because high levels of LH and/or FSH are usually a sign of normal perimenopause and menopause. As your ovaries release fewer eggs, your body makes more hormones to try to trigger ovulation.

But you may need an LH test along with other hormone tests if there is a medical reason, such as:

• Premature menopause (age 40 or younger)
• Early menopause (before age 45)
• Having symptoms that may be related to menopause, but the cause isn't clear

For men:

You may need this test if:

• You've been unable to get your partner pregnant after 12 months of trying.
• You have less interest in sex than usual.
• You have a low sperm count.
• You have a loss of muscle and/or body hair.

For men and women:

You may need an LH test if your health care provider thinks you could have a pituitary disorder. Pituitary problems can affect fertility and decrease your interest in sex. They may also cause symptoms, such as:

• Fatigue
• Weakness
• Decreased appetite and/or weight loss

For children and teens:

LH testing may be needed if puberty seems to be starting too early or too late:

• Early puberty means showing signs of sexual development before age 8 in girls and age 9 in boys.
• Delayed puberty means not showing signs of sexual development by age 13 in girls and age 14 in boys.

How to prepare

You may need to stop taking certain medicines or supplements before your test. Tell your provider everything you take. But don't stop taking any prescription medicines unless your provider tells you to.

If you have menstrual periods, you may need to have your test at a specific time during your menstrual cycle.

Sample type

Blood Urine

Other names for this test

lutropin, interstitial cell stimulating hormone, ICSH