Chorionic gonadotrophin is a glycoprotein that is secreted in all mammals and is responsible for the maintenance of pregnancy. In humans, this glycoprotein is called human chorionic gonadotrophin, and is the main substance that is tested in the pregnancy tests that are available over the counter. Human chorionic gonadotrophin in humans is produced by a fetus and this signals the brain to main a structure in the ovary called the corpus luteum. The corpus luteum is the main site of progesterone production – which is responsible for maintaining the endometrium and thereby the fetus itself. The test for this glycoprotein is called the hCG test.
The human chorionic gonadotrophin test for pregnancy is one of the confirmations of pregnancy. This test can sometimes gives false positive as the substance is similar to luteinizing hormone and follicle stimulating hormone that is responsible for ovulation. These can be eliminated by testing specially for beta hCG instead of hCG
The test of human chorionic gonadotrophin is conducted either as a blood test or a urine test. It is worth noting that this test is also done on males and not just females. In males, the center of production of hCG is in the sertoli cells. These cells are found in the testes and stimulate the production of testosterone in the body. hCG is also considered to be a banded androgenic anabolic steroid by most sporting bodies and the elevated levels of it indicate some level of doping that has been indulged in.
There is no specific preparation that needs to be done for this test though the timing of when this test is done has a lot to do with its efficacy. hCG levels are usually at their highest in the morning and ideally, the pregnancy test should be done at this time. It is curious to note that it is the elevated levels of hCG that causes the typical morning sickness that most women experience in their first trimester. Being a urine test, the dilution of urine with the consumption of excess water must be avoided. As mentioned before, the test that is normally conducted is for a subunit of hCG called beta hCG to avoid registering a false positive from luteinizing hormone and follicle stimulating hormone that cause ovulation. In IVF treatments, the positive test for hCG is a sign that ovulation is actually occurring and therefore, is a good time to collect eggs.