Luteinizing Hormone

Why It Is Done

A luteinizing hormone (LH) test may be done to:

• Help find out why a couple can't become pregnant (infertility). LH testing is often used to help evaluate:
  • A woman's egg supply. (This is called the ovarian reserve.)
  • A man's sperm count.
• Help to check for menstrual problems, such as irregular or absent menstrual periods (amenorrhea). This can help see if the woman has gone through menopause.
• Find out 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.
• Find out why sexual features or organs are not developing when they should (delayed puberty).
• Find out (usually with a urine sample) when a woman is ovulating. Home urine tests for ovulation are available.
• Check for a woman's response to medicines given to stimulate ovulation.

How To Prepare

Many medicines can change your results. Some examples are cimetidine, clomiphene, digitalis, and levodopa. 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 your luteinizing hormone (LH) test. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you take, including herbs and natural substances.

Tell your doctor if you have had a test that used a radioactive substance (tracer) in the last 7 days. Recent tests (such as a thyroid scan or bone scan) using this kind of tracer can affect your LH test results.

Let your doctor know the first day of your last menstrual period. If your bleeding pattern is light or starts with spotting, the first day is the day of heaviest bleeding.

Talk to your doctor about any concerns you have regarding the need for the test or its risks. You can also ask how it will be done and what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).

How It Is Done

Blood test

The health professional drawing blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.

For women, more than one blood sample may be needed to get a true reading of the luteinizing hormone (LH) levels. Several blood samples may be taken in one day. Or one sample may be taken each day for several days in a row.

Urine test for ovulation

To find out if you are ovulating, a sample of your first urine of the morning is usually tested. It is important to follow the package directions exactly if you are doing the test yourself at home.

• Place the collection container into the stream of urine. Collect about4 Tbsp (60 mL) of urine.
• Do not touch the rim of the container to your genital area. And do not get toilet paper, pubic hair, stool (feces), menstrual blood, or other foreign matter in the urine sample.
• Finish urinating into the toilet.

You may also be given a plastic test strip to hold in the urine stream. The test strip has a color indicator on it that can detect luteinizing hormone (LH).

How It Feels

Blood test

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Urine test

It is not painful to collect a urine sample.

What Affects the Test

Results of the test may be affected by:

• The use of certain hormones, such as those containing estrogen or progesterone. This includes birth control pills.
• The use of medicines, such as clomiphene, spironolactone, naloxone, phenothiazine, and some given for seizures (anticonvulsants).
• Diagnostic imaging procedures, such as a thyroid scan or bone scan, that use a radioactive substance (tracer) and were performed within 7 days prior to LH testing.
• Obesity.
• Hyperthyroidism.
• Liver disease.

What To Think About

• If you take a medicine that contains testosterone, estrogen, or progesterone (such as birth control pills), talk to your doctor. He or she may want you to stop taking it for several days before your test.
• You can buy home ovulation kits at a drugstore to help find the most fertile days of a woman's menstrual cycle. The kits test for LH in urine with a dipstick or test strip. You can also buy home ovulation tests that measure the amount of LH in urine and show the results on a small computer monitor.
• Other tests for ovulation include measuring basal body temperature, testing the progesterone level after ovulation in the menstrual cycle, and noting changes in cervical mucus. To learn more, see the topic Fertility Awareness.