A luteinizing hormone test measures the amount of luteinizing hormone (LH) in a sample of blood or urine. LH is produced by the pituitary gland.
- In women, LH helps regulate the menstrual cycle and egg production (ovulation). The level of LH in a woman's body varies with the phase of the menstrual cycle. It increases rapidly just before ovulation occurs, about midway through the cycle (day 14 of a 28-day cycle). This is called an LH surge. Luteinizing hormone and follicle-stimulating hormone levels rise and fall together during the monthly menstrual cycle.
- In men, LH stimulates the production of testosterone, which plays a role in sperm production.
Why It Is Done
A luteinizing hormone (LH) test may be done to:
- Help find the cause for a couple's inability to become pregnant (infertility). LH testing is commonly used to help evaluate:
- A woman's egg supply (ovarian reserve).
- A man's sperm count.
- Help evaluate menstrual problems, such as irregular or absent menstrual periods (amenorrhea). This can help determine if the woman has gone through menopause.
- Determine if a child is going through early puberty (also called precocious puberty). Puberty is early when it starts in girls younger than age 9 and in boys younger than age 10.
- Determine why sexual features or organs are not developing when they should (delayed puberty).
- Determine (usually with a urine sample) when a woman is ovulating. Home urine tests for ovulation are available.
- Monitor a woman's response to medicines given to stimulate ovulation.
How To Prepare
Many medicines, such as cimetidine, clomiphene, digitalis, and levodopa, can change your results. You may be asked to stop taking medicines (including birth control pills) that contain estrogen or progesterone or both for up to 4 weeks before having a luteinizing hormone (LH) test. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you are taking, including herbs and natural substances.
Tell your doctor if you have had a test that used a radioactive substance (tracer) within the last 7 days. Recent tests (such as a thyroid scan or bone scan) using a radioactive tracer can interfere with LH test results.