LH

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

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

This test can help find out the cause of fertility problems. A higher LH level can help find out the point in the menstrual cycle when it's best to try to conceive.

This test can also help diagnose a pituitary gland disorder.

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

• If you're biologically male, having trouble getting or keeping an erection (impotence) or having a lower sex drive.
• If you're biologically female and not pregnant or nursing, starting to make breast milk (lactation).

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

You may also need other tests for infertility. If you're biologically male, you may need a semen analysis, genetic tests, and other blood tests to measure different hormones. If you're biologically female, 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.

Test results may vary depending on your age, sex, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your doctor what your test results mean for you.

Results are given in international units per milliliter (IU/mL). Here are normal ranges.

• Male:
  • 1.24 to 7.8 IU/mL
• Female (depends on timing of menstrual cycle):
  • Follicular phase of menstrual cycle: 1.68 to 15 IU/mL
  • Midcycle peak: 21.9 to 56.6 IU/mL
  • Luteal phase: 0.61 to 16.3 IU/mL
  • Postmenopausal: 14.2 to 52.3 IU/mL

If you are biologically female, 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 polyendocrine metabolic ovarian syndrome (PMOS). Low levels of LH may mean you have a pituitary disorder, anorexia, malnutrition, or are under stress.

If you are biologically male, 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.

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

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.

If you are biologically female, your results will vary depending on what day in your menstrual cycle the test is done.

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