What Is the Connection between Luteinizing Hormone and HCG?

The connection between luteinizing hormone and human chorionic gonadotrophin (HCG) is that they are both hormones important in human reproduction. Luteinizing hormone is important in ovulation, which is a process through which a woman's ovary releases an egg for possible fertilization by sperm from a male partner. HCG, on the other hand, is a hormone a woman's body produces when she is pregnant. Interestingly, both hormones can be used to test matters related to conception. For example, tests for luteinizing hormone can indicate when a woman is likely to ovulate while tests that detect HCG can indicate whether or not a woman is pregnant.

The most significant connection between luteinizing hormone and HCG involves conception — both hormones are important in the reproductive process. Before a woman ovulates, her body produces a surge of luteinizing hormone that stimulates the release of an egg from her ovaries. If this egg is fertilized, it may then go on to implant in the uterus and develop into a baby. The cells that implant in a woman's uterus when she is pregnant, as well as the leftover egg follicle, release HCG, which is in turn detectable in a woman's blood and urine.

Another connection between luteinizing hormone and HCG is the fact that there are tests for both of these hormones. There are both blood and urine tests that detect whether a woman is having a surge of luteinizing hormone, which often means she will ovulate in the near future. Checking for the presence of a significant amount of HCG, on the other hand, is how a woman discovers she is pregnant. This test can be performed using blood or urine as well.

While it's not usually advisable to do so, there is some evidence that a woman can use a urine ovulation test as a pregnancy test. This is due to the fact that luteinizing hormone and HCG have a similar makeup. Despite this, however, women cannot use pregnancy tests as ovulation tests, as they won't detect luteinizing hormone. Additionally, most experts recommend against using ovulation tests as pregnancy tests simply because the test taker cannot be sure it is accurate if she's not using the right test for the job.

Another reason experts often recommend against using luteinizing hormone and HCG tests interchangeably is the fact that they can produce confusing results. If a woman uses a urine ovulation test as a pregnancy test, she may see two lines that would normally indicate that the test is working and that there is luteinizing hormone present. When this type of test is used in this manner, however, it indicates the presence of either luteinizing hormone or HCG, and the woman has to take a pregnancy test to figure out which one.