Luteinizing Hormone Test
Luteinizing Hormone Test
The luteinizing hormone (LH) test is a test of the blood or urine to measure the level of luteinizing hormone (lutropin). This hormone level is highest immediately before a woman ovulates during her menstrual cycle.
The LH test is frequently used to determine the timing of ovulation. Couples who are trying to become pregnant may use information about the timing of ovulation to improve their chance of conception. The LH test and other hormone tests may be used during infertility screening to chart a woman's menstrual cycle. It may also be used during preparation for in vitro fertilization, to determine when eggs are mature and ready to be removed from the ovary.
Lutenizing hormone is a hormone released by the pituitary gland, a small gland at the base of the brain. The hormone stimulates the ovaries to produce and release eggs each month during the menstrual cycle. The level of LH in the blood is highest before ovulation. This increase in hormone level is sometimes called a "surge." A urine or blood sample can be analyzed by a laboratory for the level of LH present. An LH test may be used as part of an infertility screening to determine if there is a hormonal imbalance that might make it difficult to become pregnant. If fertility drugs are given to stimulate ovulation, an LH test can help determine the best time for sexual intercourse. The LH test may also be used to determine when eggs are mature enough to be surgically removed from the ovary as part of the in vitro fertilization process. LH tests may also aid in the diagnoses of polycystic ovary disease, premature ovarian failure, and menopause.
A urine LH detection kit is also available for use at home. These are sometimes called "ovulation tests" and are similar to home pregnancy test kits. A sample of the woman's first morning urine is tested with the materials provided in the kit. These home tests are often used by women who want to become pregnant. By monitoring levels of LH and watching for the "surge," they can time sexual intercourse to coincide with ovulation, increasing the chance that the egg will be fertilized.
If a blood sample is taken, the skin around the vein where the needle will be inserted is swabbed with an antiseptic. No special preparation is necessary for collection of a urine sample.
No special aftercare is required. If the blood is tested, as with any blood sampling, the area where the needle was inserted should be kept clean.
There are no significant risks associated with either the blood or urine test for LH.
The level of LH in the blood or urine will vary depending on when the sample was taken during the menstrual cycle. LH levels will be highest around the time of ovulation, about halfway between a woman's menstrual periods. Levels will be lower during the rest of the month. Women who have already experienced menopause will normally have lower LH levels.
LH levels that remain low throughout the menstrual cycle may indicate a hormonal imbalance that could prevent ovulation. Additional testing may be required if this test is done as part of an infertility screening.
Lutropin — Another term for luteinizing hormone, this hormone stimulates the development and release of the egg from the ovary.
Zaret, Barry L., et al., editors. The Patient's Guide to Medical Tests. Boston: Houghton Mifflin, 1997.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.