A luteinizing hormone test measures the
amount of luteinizing
hormone (LH) in a sample of blood or urine. LH is
produced by the
- 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
Why It Is Done
A luteinizing hormone (LH) test may be
- 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
- Determine if a child is going
puberty (also called precocious puberty). Puberty is
early when it starts in girls younger than age 9 and in boys younger than age
- 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
- Monitor a woman's response to medicines given to
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
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.