Health library

Search by Specialty
Health Encyclopedia -Search by letter
a b c d e f g h i j k l m n o p q r s t u v w x y z

HCG (Blood)

Does this test have other names?

Human chorionic gonadotropin hormone test

What is this 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, when you're about six weeks pregnant. 

Why do I need this test?

Your health care 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 doctor 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. 

What other tests might I have along with this test? 

Your doctor 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 doctor figure out if you are at risk for miscarriage or ectopic pregnancy. 

What do my test results mean?

A result for a lab test may be affected by many things, including the method the laboratory uses to do the test. 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 health care 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. 

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

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. 

What might affect my test results?

This test is quite reliable, but false-positives can be caused by:

  • Certain tumors that make HCG

  • Medications containing HCG, such as certain drugs used in fertility treatments

  • Recent loss of pregnancy; it can take 60 days for HCG levels to return to normal 

How do I get ready for this test?

You don't need to prepare for this test. But be sure your doctor 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.