Human chorionic gonadotropin hormone test, serum pregnancy test
Human chorionic gonadotropin (HCG) is a type of hormone. Both men and women have small amounts of HCG in their body at all times. When a woman is pregnant, her body produces much more HCG than usual. In a healthy pregnancy, the amount of HCG in the blood increases substantially throughout the first three months. This blood test measures how much HCG is in your blood.
This test is the gold standard for determining whether you are pregnant. It shows that you are pregnant before an imaging test, such as an ultrasound, can detect a fetus. Ultrasound can show you that you are pregnant when HCG rises to 1,000 IU/L or greater.
Your healthcare provider might order this test if you have vaginal bleeding or cramping. This might indicate that you could have an ectopic pregnancy or could lose your unborn baby. Your healthcare provider might also want to know how your pregnancy is progressing over a few days, so he or she may order this test two or more times, several days apart.
Your healthcare provider might also order an ultrasound to screen for certain birth defects. Your blood may also be checked for two other hormones, estradiol and progesterone. Your levels of estradiol, a form of estrogen, can show how well the placenta is working. Progesterone levels also rise during pregnancy and can help your healthcare provider figure out if you are at risk for miscarriage or ectopic pregnancy.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.
Normal levels of HCG in men and premenopausal women range from 0.02 to 0.8 IU/L. In early pregnancy, HCG levels can double every few days, peaking by about 10 weeks. After that, levels can either hold steady or begin to decline. Normal HCG levels during pregnancy can range from 20,000 to 200,000 IU/L.
Sometimes, measuring change in HCG levels over time can provide useful information. If HCG levels do not change as expected, it may mean the pregnancy could be lost.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
This test is quite reliable, but false-positives can be caused by:
Certain tumors that make HCG
Medicines containing HCG, such as those used in fertility treatments
Recent loss of pregnancy; it can take 60 days for HCG levels to return to normal
You don't need to prepare for this test. But be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.