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, so that a mature egg is released from the ovaries. 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. An elevated 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.
You may need this test if you are infertile 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 prolactinoma, or a benign tumor in the pituitary gland. Symptoms include:
Impotence or lower sex drive in men
Lactation in women who aren't pregnant or nursing
You may also have this test if you are having irregular menstrual periods.
Your doctor may also order other tests for infertility. If you're a man, your doctor may order a semen analysis, genetic tests, and other blood tests to measure different hormones. If you're a woman, your doctor may order other hormone-level blood tests, basal body temperature testing, and a hysteroscopy to examine the inside of your uterus.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Results are given in international units per liter (IU/L). The normal range for a woman varies, depending on her menstrual cycle. Here are normal ranges:
Men: 1.24 to 7.8 IU/L
Women, follicular phase of menstrual cycle: 1.68 to 15 IU/L
Women, midcycle peak: 21.9 to 56.6 IU/L
Women, luteal phase: 0.61 to 16.3 IU/L
Women, postmenopausal: 14.2 to 52.3 IU/L
Girls, ages 1 to 10 years: 0.03 to 3.9 IU/L
If you're a woman, abnormally high levels of LH during non-ovulatory 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 creation.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
If you're a woman, your results will vary depending on what day in your menstrual cycle the test is done.
You don't need to prepare for this test. But 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 illicit drugs you may use.