An LH urine test detects a rise in lutenizing hormone (LH). Such a rise, or surge, signals the ovary to release the egg. This at-home test is often used by women to help predict ovulation.

Ovulation prediction test kits usually come with five to seven sticks. You may need to test for several days to detect a surge in LH. The specific time of month that you start testing depends on the length of your menstrual cycle. For example, if your normal menstrual cycle is 28 days, you'll need to test on day 11 -- that is, the 11th day after you started your period.

You will need to urinate on the test stick, or place the stick into urine that has been collected into a sterile container. The test stick will turn a certain color or display a positive sign if a surge it detected. A positive result means you should ovulate in the next 24 to 36 hours, but this may not be the case for all women. The kit's instruction booklet will tell you how to properly read the results.

If you miss a day, you may miss your surge. You may also miss recording a surge if you have an irregular menstrual cycle.

Do not drink large amounts of fluids before using the test.

Ask your doctor if you need to stop taking certain drugs before using this test.

Drugs that can decrease LH measurements include estrogens, progesterone and testosterone. Estrogens and progesterone may be found in birth control pills and hormone replacement therapy.

The drug clomiphene citrate (Clomid) can increase LH levels. This drug is used to help trigger ovulation. Women taking this drug should wait three days after stopping the medicine before checking their LH levels.

The test involves normal urination. There is no pain or discomfort.

The test is most often done to determine when a women will ovulate. It may also be used to determine if you need to adjust doses of certain medications.

A positive result indicates an an "LH surge" and is a sign that ovulation may soon occur. Read your specific manufacturer's instruction booklet for complete details.

Rare false positive results can occur. This means the test kit may falsely predict ovulation.

If you are unable to detect a surge or do not become pregnant after using an ovulation prediction kit for several months, contact your doctor. You may need to see an infertility specialist.

LH urine tests are not the same as at home fertility monitors. Fertility montiors are digital handheld devices that predict ovulation based on electrolyte levels in saliva, LH levels in urine, or your basal body temperature. These devices can store ovulation information for several menstrual cycles.

Stenchever A. Comprehensive Gynecology. 4th ed. St. Louis, Mo: Mosby; 2001.

Jose-Miller AB. Infertility. Am Fam Physician. 15 Mar 2007; 75(6): 849-56.

Speroff, L, Fritz, MA, eds. Clinical Gynecologic Endocrinology and Infertility. 7th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2005