What is a 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.

Other names: lutropin, interstitial cell stimulating hormone, ICSH

What is it used for?

LH testing is used to help diagnose conditions that cause too much or too little LH. The specific way the test is used depends on your sex, age, and symptoms.

In women, an LH tests may be used to:

• Help find the cause of infertility.
• Find out when ovulation is about to happen if a woman is trying to get pregnant. Usually at-home tests are used to track ovulation. These tests measure LH in urine (pee).
• Check for medical conditions that affect the ovaries.
• Find the reason for irregular or stopped menstrual periods in women of childbearing age.
• Help find out if menopause, or perimenopause may have begun:
  • Menopause happens when the ovaries stop making certain hormones, and menstrual periods have stopped for 12 months in a row. This usually happens around age 50.
  • Perimenopause is the time leading up to menopause when hormones and periods begin to change. It usually starts around age 45.

In men, an LH test may be used to:

• Help find the cause of:
  • Infertility
  • A low sperm count
  • Low testosterone levels
  • A low sex drive
• Check for medical conditions that affect the testicles

In women and men, LH testing may be used to help diagnose disorders of the:

• Pituitary gland
• Hypothalamus

In children and teens, LH testing is most often used to help find out if a medical disorder is causing early or delayed (late) puberty.

An LH test is usually used with a blood test to check the levels of another hormone called follicle-stimulating hormone (FSH). These two hormones work closely together to control sexual development and reproduction. Blood tests to check estrogen, testosterone, and progesterone levels are also commonly used with LH testing.

Why do I need an LH test?

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.

What happens during an LH levels test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

If you're using at-home urine testing to track ovulation, follow the instructions that come with your LH testing kit.

Will I need to do anything to prepare for the test?

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.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There is no risk to a urine test.

What do the results mean?

To understand the results of your LH test, your provider will consider your sex, age, symptoms, medical history, and the results of other hormone tests, especially your level of follicle stimulating hormone (FSH). Your provider can explain what the results of your LH test mean.

Higher LH in adults:

• In women who have menstrual periods, LH levels change through the month. An increase in LH a couple of weeks after your period usually means you're ovulating normally. But high LH levels through the month may mean your ovaries aren't working properly. If you are:
  • Childbearing age, higher than normal LH levels may mean you may have a disorder that affects your ovaries work, such as:
    • Ovaries that never developed normally
    • Primary ovarian insufficiency (POI)
    • Polycystic ovary syndrome (PCOS)
    • Thyroid diseases or adrenal gland disorders
    • A chromosomal disorder, such as Turner syndrome
  • 45 or older, high LH levels may mean you are approaching menopause.
• In men, high levels of LH may be caused by:
  • A germ cell tumor (a tumor that starts in the cells that become sperm)
  • Mumps
  • A physical injury to the testicles
  • Testicles that never developed normally
  • A chromosomal disorder, such as Klinefelter syndrome
• In women and men, high LH levels may be a sign of damage to the ovaries or testicles from:
  • Autoimmune disease
  • Radiation therapy and/or chemotherapy

Lower-than-normal levels of LH in adults are often a sign of a problem with the pituitary gland or hypothalamus. These problems may make it hard for your body to make enough LH and FSH.

In women, low LH and FSH levels with missed periods may also be linked to extreme exercise, malnutrition, stress, or being very underweight.

Generally, in children with signs of early sexual development (before age 8 in girls or age 9 in boys):

• High levels of LH and FSH mean the child has early puberty, also called precocious puberty. In most cases, the cause is unknown. But in certain cases, the cause is a problem in the brain, such as:
  • A brain tumor
  • A past brain injury
  • A past brain infection, such as meningitis or encephalitis
• Normal levels of LH and FSH mean the child has a type of early puberty called peripheral precocious puberty. This often means that a disorder in the testicles, ovaries, or adrenal glands is causing higher than normal levels of estrogen or testosterone. Exposure to medicines that contain sex hormones may also cause this type of early puberty.

Generally, in teens with no signs of sexual development by age 13 for girls or age 14 for boys, levels of LH and FSH may be low, normal, or high depending on the cause of delayed puberty. Many teens with delayed puberty are healthy and go through normal puberty at a later age. But delayed puberty may be caused by certain medical conditions, such as:

• Poor nutrition from a long-term illness or eating disorder
• Hypogonadism, which is when the ovaries or testicles make little or no hormone. It may be caused by:
  • Certain genetic disorders, including Kallmann syndrome
  • Tumors in the brain or pituitary gland
  • Turner syndrome in girls
  • Klinefelter syndrome in boys
  • Certain autoimmune disorders
  • Radiation therapy or chemotherapy

If you have questions about test results, talk with your or your child's provider.

Learn more about laboratory tests, reference ranges, and understanding results.