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Luteinizing Hormone (Blood)

Does this test have other names?

LH

What is this test?

This test measures the level of luteinizing hormone (LH) in your blood.

LH is made by your pituitary gland. In women, the pituitary sends out LH during the ovulation part of the menstrual cycle. This tells the ovaries to release a mature egg. In men, LH causes the testes to make testosterone.

This test can help find out the cause of fertility problems in both men and women. A higher LH level can help a woman find out the point in her cycle when it's best to try to conceive.

This test can also help diagnose a pituitary gland disorder.

Why do I need this test?

You may need this test if you are having trouble getting pregnant (infertility) and your healthcare provider needs to find out the cause. You may also have this test if you have symptoms of a pituitary disorder, such as a benign tumors in the pituitary gland (called a prolactinoma). Symptoms include:

  • Men have trouble getting or keeping an erection (impotence) or have a lower sex drive

  • Women who aren't pregnant or nursing start to produce breastmilk (lactation)

You may also have this test if you are having irregular menstrual periods.

What other tests might I have along with this test?

You may also need other tests for infertility. If you're a man, you may need a semen analysis, genetic tests, and other blood tests to measure different hormones. If you're a woman, you may order other hormone-level blood tests, genetic tests, and basal body temperature testing. You may also need a pelvic ultrasound and a hysteroscopy to look at the inside of your uterus.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

Results are given in international units per liter (IU/L). The normal range for a woman varies, depending on the timing of her menstrual cycle. Here are normal ranges:

  • Men: 1.42 to 15.4 IU/L

  • Women, follicular phase of menstrual cycle: 1.37 to 9 IU/L

  • Women, midcycle peak: 6.17 to 17.2 IU/L

  • Women, luteal phase: 1.09 to 9.2 IU/L

  • Women, postmenopausal: 19.3 to 100.6IU/L

If you're a woman, abnormally high levels of LH during nonovulatory times in your menstrual cycle may mean you are in menopause. It may also mean that you have a pituitary disorder or polycystic ovary syndrome. Low levels of LH may mean you have a pituitary disorder, anorexia, malnutrition, or are under stress.

If you're a man, abnormally high LH levels along with low levels of testosterone may mean that your testicles aren't responding to LH's signal to make more testosterone. Low levels of LH may mean that your pituitary gland isn't making enough LH. That can lead to too little testosterone production.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

If you're a woman, your results will vary depending on what day in your menstrual cycle the test is done.

How do I get ready for this test?

You don't need to get ready for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.  

Medical Reviewers:

  • Chad Haldeman-Englert MD
  • Maryann Foley RN BSN
  • Raymond Turley Jr PA-C