This test measures the level of luteinizing hormone (LH) in your blood. LH is made by your pituitary gland, a small gland located underneath the brain. LH plays an important role in sexual development and functioning.
- In women, LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is known as ovulation. LH levels quickly rise just before ovulation.
- In men, LH causes the testicles to make testosterone, which is important for producing sperm. Normally, LH levels in men do not change very much.
- In children, LH levels are usually low in early childhood, and begin to rise a couple of years before the start of puberty. In girls, LH helps signal the ovaries to make estrogen. In boys, it helps signal the testes to make testosterone.
Too much or too little LH can cause a variety of problems, including infertility (the inability to get pregnant), menstrual difficulties in women, low sex drive in men, and early or delayed puberty in children.
Other names: lutropin, interstitial cell stimulating hormone
What is it used for?
An LH test works closely with another hormone called follicle-stimulating hormone (FSH) to control sexual functions. So an FSH test is often done along with an LH test. These tests are used in different ways, depending on whether you are a woman, man, or child.
In women, these tests are most often used to:
- Help find the cause of infertility
- Find out when ovulation occurs, this is the time when you are most likely to get pregnant.
- Find the reason for irregular or stopped menstrual periods.
- Confirm the start of menopause, or perimenopause. Menopause is the time in a woman’s life when her menstrual periods have stopped and she can’t become pregnant anymore. It usually starts when a woman is around 50 years old. Perimenopause is the transition period before menopause. It can last for several years. LH testing may be done towards the end of this transition.
In men, these tests are most often used to:
- Help find the cause of infertility
- Find the reason for a low sperm count
- Find the reason for low sex drive
In children, these tests are most often used to help diagnose early or delayed puberty.
- Puberty is considered early if it starts before age 9 in girls and before age 10 in boys.
- Puberty is considered delayed if hasn’t started by age 13 in girls and by age 14 in boys.
Why do I need an LH test?
If you are a woman, you may need this test if:
- You’ve been unable to get pregnant after 12 months of trying.
- Your menstrual cycle is irregular.
- Your periods have stopped. The test may be used to find out if you have gone through menopause or are in perimenopause.
If you are a man, you may need this test if:
- You’ve been unable to get your partner pregnant after 12 months of trying.
- Your sex drive is decreased.
Both men and women may need testing if they have symptoms of a pituitary disorder. These include some of the symptoms listed above, as well as:
- Weight loss
- Decreased appetite
Your child may need an LH test if he or she is does not seem to be starting puberty at the right age (either too early or too late).
What happens during an LH levels test?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
If you are a woman that has not gone through menopause, your provider may want to schedule your test at a specific time during your menstrual cycle.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
The meaning of your results will depend on whether you are a woman, man, or child.
If you are woman, high LH levels may mean you:
- Are not ovulating. If you are of childbearing age, this may mean you have a problem in your ovaries. If you are older, it may mean you have started menopause or are in perimenopause.
- Have polycystic ovary syndrome (PCOS). PCOS is a common hormone disorder affecting childbearing women. It is one of the leading causes of female infertility.
- Have Turner syndrome, a genetic disorder affects sexual development in females. It often causes infertility.
If you are woman, low LH levels may mean:
- Your pituitary gland is not working correctly.
- You have an eating disorder.
- You have malnutrition.
If you are a man, high LH levels may mean:
- Your testicles have been damaged due to chemotherapy, radiation, infection, or alcohol abuse.
- You have Klinefelter’s syndrome, a genetic disorder that affects sexual development in males. It often causes infertility
If you are a man, low LH levels may mean you have a disorder of the pituitary gland or the hypothalamus, a part of the brain that controls the pituitary gland and other important body functions.
In children, high LH levels, along with high levels of follicle-stimulating hormone, may mean puberty is about to start or has already started. If this is happening before age 9 in a girl or before age 10 in a boy (precocious puberty), it may be a sign of:
- A disorder of the central nervous systems
- A brain injury
Low LH and follicle-stimulating hormone levels in children may mean be a sign of delayed puberty. Delayed puberty may be caused by:
- A disorder of the ovaries or testicles
- Turner syndrome in girls
- Klinefelter’s syndrome in boys
- An infection
- A hormone deficiency
- An eating disorder
If you have questions about your results or child’s results, talk to your health care provider.
Is there anything else I need to know about an LH test?
There is an at-home test that measures LH levels in urine. The kit is designed to detect the rise in LH that happens just before ovulation. This test may help you figure out when you will be ovulating and have the best chances of getting pregnant. But you should not use this test to prevent pregnancy. It is not reliable for that purpose.
Courtesy of MedlinePlus from the National Library of Medicine.