Luteinizing Hormone (LH) Blood Test

The LH blood test measures the amount of luteinizing hormone (LH) in blood. LH is a hormone released by the pituitary gland, located on the underside of the brain.

How to Prepare for the Test?

Your health care provider will ask you to temporarily stop medicines that may affect the test results. Be sure to tell your provider about all the medicines you take. These include:

  • Birth control pills.
  • Hormone therapy.
  • Testosterone.
  • DHEA (a supplement).

If you are a woman of childbearing age, the test may need to be done on a specific day of your menstrual cycle. Tell your provider if you have recently been exposed to radioisotopes, such as during a nuclear medicine test.

Why the Test is Performed?

In women, an increase in LH level at mid-cycle causes release of eggs (ovulation). Your doctor will order this test to see if:

  • You are ovulating, when you are having trouble getting pregnant or have periods that are not regular.
  • You have reached menopause.

If you are a man, the test may be ordered if you have signs of infertility or lowered sex drive. The test may be ordered if you have signs of a pituitary gland problem.

Normal Results

Normal results for adult women are:

  • Before menopause – 5 to 25 IU/L.
  • Level peaks even higher around the middle of the menstrual cycle.
  • Level then becomes higher after menopause – 14.2 to 52.3 IU/L.

LH levels are normally low during childhood.

Normal result for men over 18 years of age is around 1.8 to 8.6 IU/L.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test result.

What Abnormal Results Mean?

In women, a higher than normal level of LH is seen:

  • When women of childbearing age are not ovulating.
  • When there is an imbalance of female sex hormones (such as with polycystic ovary syndrome).
  • During or after menopause.
  • Turner syndrome (rare genetic condition in which a female does not have the usual pair of 2 X chromosomes).
  • When the ovaries produce little or no hormones (ovarian hypofunction)

In men, a higher than normal level of LH may be due to:

  • Absence of testes or testes that do not function (anorchia).
  • Problem with genes, such as Klinefelter syndrome.
  • Endocrine glands that are overactive or form a tumor (multiple endocrine neoplasia).

In children, a higher than normal level is seen in early (precocious) puberty.

A lower than normal level of LH may be due to the pituitary gland not making enough hormone (hypopituitarism).

Keywords: Luteinizing hormone blood test; LH blood test.

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.