This urine test detects LH levels above a certain threshold.

Urine is collected. A sample of the urine is then applied to the test kit. The first urine of the day should not be used for this test.

The test is done to determine the time of ovulation and is also used to adjust doses of certain medications.

The anterior pituitary gland secretes hormones called gonadotropins (LH is one of these), which stimulate the ovary to prepare a follicle to release an egg. Once the follicle has matured, a dramatic rise in LH levels (known as the "LH surge") signals the ovary to release the egg (this is ovulation). Ovulation typically occurs 10-12 hours after the peak of the LH surge.

Most test kits can detect urinary LH levels as low as 20-40 IU/L (international units per liter). An LH "surge" is detected if the urinary LH is above the threshold. However, variations between different urinary LH kits are common. Check with the manufacturer to find out the detection limit of their kit in IU/L.

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.

It can be helpful to know the exact time of ovulation when trying to get pregnant. However, research shows that home urinary LH tests are no more likely to help a woman conceive than is charting her basal body temperature during initial attempts to induce ovulation with the drug clomiphene citrate (Clomid).