Test Quick Guide

Luteinizing hormone (LH) is associated with reproduction. This test measures the amount of LH in the blood. Because it helps stimulate the release of an egg from the ovary (ovulation) in women or testosterone production in men, the test is usually used to pinpoint the cause of infertility, identify possible pituitary disorders, and diagnose conditions that impact the function of the ovaries or testicles.

About the Test

Purpose of the test

In both women and men, the LH test is often used in conjunction with other tests including follicle-stimulating hormone (FSH), testosterone, estradiol, and progesterone to help diagnose:

  • The cause of infertility
  • Pituitary disorders that can affect LH production
  • Conditions that affect the function of the ovaries or testicles

In women, LH tests are useful for:

  • Investigating irregular periods (menstrual cycles)
  • Multiple urine LH tests may be ordered to evaluate LH levels during the menstrual cycle. These LH “spot tests” can be performed at home and used to detect the surge in LH that indicates that ovulation will occur in the next one to two days. The tests can help determine when a woman is likely to be the most fertile.

In children, FSH and LH tests are used in the diagnosis of delayed and precocious (early) puberty. Irregular timing of puberty may be an indication of a more serious problem involving the hypothalamus, the pituitary gland, the ovaries or testicles, or other systems. The measurement of LH and FSH can help in differentiating between benign symptoms and true disease.

What does the test measure?

LH is produced by the pituitary gland, a small organ located in the center of the head behind the sinus cavity at the base of the brain. Control of LH production is a complex system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries and testicles.

In women of childbearing age, several hormones (LH, FSH, estrogen and progesterone) rise and fall in a specific sequence during each menstrual cycle. Results of an LH test are typically considered with results of other hormone tests, such as FSH, estrogens, and/or testosterone.

Womens’ menstrual cycles are divided into follicular and luteal phases, with each phase lasting about 14 days. Near the end of the follicular phase, there is a mid-cycle surge of FSH and LH. This surge triggers ovulation, causing the rupture of the egg follicle on the ovary and the release of the egg.

During the luteal phase, the site where the egg follicle ruptured becomes a “corpus luteum.” LH release stimulates the corpus luteum to start producing progesterone. FSH and LH levels decline, while progesterone and estradiol concentrations increase. These hormone levels decrease in turn after several days if the egg is not fertilized. Menstruation starts and when it ends, the cycle begins again.

As a woman ages and menopause approaches, ovarian function wanes and eventually ceases. As this occurs, FSH and LH levels rise.

In men, LH stimulates Leydig cells in the testicles to produce testosterone. LH levels are relatively constant in men after puberty. A high testosterone level provides negative feedback to the pituitary gland and the hypothalamus, thus decreasing the amount of LH released.

In infants and children, LH levels rise shortly after birth and then fall to very low levels (by six months in boys and one to two years in girls). At about six to eight years, levels again rise before the beginning of puberty and the development of secondary sexual characteristics.

When should I get this test?

In adults, LH (and FSH) tests may be ordered when:

  • A woman is having difficulty getting pregnant or has irregular or an absence of menstrual periods
  • When a man’s partner cannot get pregnant, when he has a low testosterone level, or when he has low muscle mass or decreased sex drive, for example
  • When a health care practitioner suspects that a pituitary disorder is present; this can affect the production of several different hormones so there may be signs and symptoms in addition to infertility

In children, LH and FSH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon). Signs of puberty may include:

  • Breast enlargement in girls
  • Growth of pubic hair
  • Growth of testicles and penis in boys
  • Beginning of menstruation in girls

Finding a Luteinizing Hormone Test

How can I get an LH test?

An LH test is typically ordered by your doctor and can be given at a medical facility or laboratory. Sometimes, it may make sense to take a combined FSH and LH blood test.

Can I take the test at home?

There are LH blood spot home testing kits that you can order and take yourself. Depending on what you are using it for, it might be more convenient to take the test at home. It’s always wise to consult with your health care provider if you are experiencing any health issues, however.

How much does the test cost?

The cost of an LH test depends on where the test is performed and what your health insurance coverage is like. If you have insurance, you may still be required to make a copayment or deductible payment depending on your plan.

Ask your doctor or your insurance plan about the expected costs of LH testing.

Taking an LH Test

An LH test is done by taking a sample of blood, usually from a vein in your arm. For at-home LH tests, a smaller blood sample is collected using a fingerstick.

Before the test

There are no restrictions as far as eating or drinking before taking an LH blood test. However, if you take high-dose biotin supplements (vitamin B7), stop taking them 24 hours before your LH blood test as it can impact the test’s accuracy.

During the test

An LH blood test involves a phlebotomist taking blood from a vein in your arm. First, they will disinfect the area with an alcohol wipe and tie an elastic band around your upper arm to help expose the vein. Next, they will insert the needle, and you will feel a slight pinch. The blood will be collected into a tube. Once enough blood is taken, the band will be removed, and they will pull out the needle and cover the blood draw area with gauze and a bandage.

If you’re using an at-home LH test kit, you will collect small blood samples from the end of the finger by using a small lancet. The test kit will include a blood spot card on which you will place the blood samples as indicated.

After the test

Once the LH blood test is completed, there are no restrictions or side effects to be concerned about. You may experience minor bruising at the site of the blood draw. If you did a fingerstick, that should heal fairly quickly as well.

LH Test Results

Receiving test results

Test results for LH typically take one to three business days. You will usually be contacted by your health care provider or laboratory with results, or if a patient portal is available, you may be able to access the test findings in your account.

If you are using an at-home blood spot test for LH, results may take one to two weeks after the specimen is received by the laboratory.

Interpreting test results

The following are considered general LH normal values:

  • For women in the follicular phase (menstruating still): between 1 and 12 IU/L
  • For women at their peak of their menstruation: between 9 and 80 IU/L
  • Post-menopausal women: greater than 30
  • Men between the ages of 20 and 70 years: between 2 and 9 IU/L

Increased levels of LH and FSH are seen in the following:

Developmental defects:

  • Failure to develop ovaries (ovarian agenesis)
  • Chromosome disorder, such as Turner’s syndrome
  • Defect in steroid production by the ovaries, such as 17 alpha hydroxylase deficiency

Damage or injury to the ovaries due to:

  • Exposure to radiation
  • Chemotherapy
  • Autoimmune disease

Underlying conditions that affect ovary function, such as:

  • Polycystic ovary syndrome (PCOS)
  • Adrenal disease
  • Thyroid disease

In women who are trying to become pregnant, multiple LH tests can be used to detect the surge that precedes ovulation. An LH surge indicates that ovulation has occurred.

Low levels of LH and FSH may be seen in problems with the pituitary or hypothalamus.

In men, high LH levels may indicate a condition affecting the testicles themselves. Some examples include:

  • Viral infection (mumps)
  • Trauma, injury
  • Exposure to radiation
  • Chemotherapy
  • Autoimmune disease
  • Germ cell tumor
  • Failure to develop normal gonads (gonadal agenesis or gonadal dysgenesis)
  • Chromosome disorder, such as Klinefelter’s syndrome

Low levels of LH and FSH may indicate a problem with the pituitary or hypothalamus.

In young children, higher levels of LH and FSH than expected when paired with the development of secondary sexual characteristics at an unusually young age are an indication of early puberty. Much more common in girls than in boys, this premature development is usually due to a problem with the central nervous system and can have a few different underlying causes. Examples include:

  • Central nervous system tumor
  • Brain injury, trauma
  • Inflammation within the central nervous system (e.g., meningitis, encephalitis)

Normal prepubescent levels of LH and FSH in children exhibiting signs of puberty (e.g., development of pubic hair and acne) may indicate a condition brought on by elevated levels of the hormones estrogen or testosterone. This may be caused by:

  • Exposure to estrogen or testosterone creams or gels
  • Premature adrenarche (an early awakening of the adrenal glands)
  • Tumors that produce hormones
  • Adrenal gland tumors
  • Ovarian tumors or cysts
  • Testicular tumors

Normal FSH and LH levels with a few signs of puberty may be a normal variation of puberty.

In delayed puberty, LH and FSH levels can be high, normal, or below what is expected for a youth within this age range. The test for LH response to gonadotropin-releasing hormone (GnRH) in addition to other testing may help to diagnose the reason for the delayed puberty. Some of the causes for delayed puberty can include:

  • Failure of the ovaries or testicles
  • Hormone deficiency
  • Turner’s syndrome
  • Klinefelter’s syndrome
  • Chronic infections
  • Cancer
  • Eating disorder (anorexia nervosa)

It’s always important to follow up with your doctor when you get blood testing like an LH test. Some questions to consider include:

  • What are the possible explanations for my LH level?
  • Should I do a repeat LH test?
  • Is there any other follow up testing I need to do?

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