Human Chorionic Gonadotropin (HCG)

Test Overview

The human chorionic gonadotropin (hCG) test is done to check for the hormone hCG in blood or urine. Some hCG tests measure the exact amount. Some just check to see if the hormone is present. HCG is made by the placenta during pregnancy. The test can be used to see if a woman is pregnant. Or it can be done as part of a screening test for birth defects.

HCG may also be made by certain tumors, especially those that come from an egg or sperm. (These are called germ cell tumors.) HCG levels are often tested in a woman who may have tissue that is not normal growing in her uterus. The test also may be done to look for molar pregnancy or a cancer inside the uterus. Several hCG tests may be done after a miscarriage to be sure a molar pregnancy is not present. In a man, hCG levels may be measured to help see if he has cancer of the testicles.

HCG to detect pregnancy

An egg is normally fertilized by a sperm cell in a fallopian tube. Within 9 days the fertilized egg moves down the fallopian tube into the uterus. It then attaches (implants) to the wall of the uterus. After the fertilized egg implants, the growing placenta starts releasing hCG into your blood. Some hCG also gets passed in your urine. HCG can be found in the blood before the first missed menstrual period. This can be as early as 6 days after the egg implants.

HCG helps to keep your pregnancy going. It also affects the development of your baby (fetus). Levels of hCG go up fast in the first 14 to 16 weeks after your last menstrual period. They are the highest around the 14th week following your last period. They then go down gradually. The amount that hCG goes up early in pregnancy can give information about your pregnancy and the health of your baby. Soon after delivery, hCG can no longer be found in your blood.

More hCG is released in a multiple pregnancy, such as twins or triplets, than in a single pregnancy. Less hCG is released if the fertilized egg implants in a place other than the uterus, such as in a fallopian tube. This is called an ectopic pregnancy.

HCG blood tests

The level of hCG in the blood is often used as part of a screening for birth defects in a maternal serum triple or quadruple screening test. These tests are usually done between 15 and 20 weeks of pregnancy to check the levels of three or four substances in a pregnant woman's blood. The triple screen checks hCG, alpha-fetoprotein (AFP), and a type of estrogen (unconjugated estriol, or uE3). The quad screen checks these substances and the level of the hormone inhibin A. The levels of these substances-along with a woman's age and other factors-help the doctor figure out the chance that the baby may have certain problems or birth defects.

Pregnancy: Should I Have Screening Tests for Birth Defects?

In some cases, screening tests are combined in the first trimester to look for Down syndrome. This screening test uses an ultrasound to measure the thickness of the skin at the back of the fetus's neck (nuchal translucency). It also includes a blood test for the levels hCG and a protein called pregnancy-associated plasma protein A (PAPP-A). This test works about as well as the second-trimester maternal serum quad screening.^{footnote 1}

HCG urine tests

HCG urine tests are usually used for regular pregnancy testing. The test does not measure the exact amount of hCG, but it shows if hCG is present. Home versions of this test are easy to find and buy.

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Pregnancy: Should I Have Screening Tests for Birth Defects?

Why It Is Done

A test for human chorionic gonadotropin (hCG) is done to:

See if you are pregnant.
Find an ectopic pregnancy.
Find and check the treatment of a molar pregnancy.
See if there is a greater chance of birth defects such as Down syndrome. The test is done with other screening tests.
Find and check on the treatment of a cancer that develops from an egg or sperm (germ cell cancer), such as cancer of the ovaries or testicles. In such cases, a test for alpha-fetoprotein may be done along with a test for hCG.

How To Prepare

If a blood sample is collected, you do not need to do anything before you have this test.

If a urine test is done, the first urine of the day is generally the best to use because it has the highest level of hCG. A urine sample collected at least 4 hours after you last urinated will also have high amounts of hCG.

How It Is Done

Human chorionic gonadotropin (hCG) may be measured in a sample of blood or urine.

Blood sample collection

The health professional drawing blood will:

Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. If the needle is not placed correctly or if the vein collapses, more than one needle stick may be needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is collected.
Put a gauze pad or cotton ball over the needle site as the needle is removed.
Put pressure on the site and then put on a bandage.

Urine collection

If possible, collect a sample from the first urine of the day.

Place the collection container into the stream of urine. Collect about4 Tbsp (60 mL) of urine.
Do not touch the rim of the container to your genital area. And do not get toilet paper, pubic hair, stool (feces), blood, or other foreign matter in the urine sample.
Finish urinating into the toilet or urinal.
Carefully replace the lid on the container. Return it to the lab. If you are collecting the urine at home and can't get it to the lab in an hour, refrigerate it.

How It Feels

Blood test

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

You may feel anxious while you wait for results of an hCG test done to check the health of your baby.

Urine test

In most cases, there is no pain with collecting a urine sample.

Risks

Risks of a blood test

There is very little chance of a problem from having a blood sample taken from a vein.

You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.

Urine test

Collecting a urine sample does not cause problems.

Results

The human chorionic gonadotropin (hCG) test is done to measure the amount of the hormone hCG in blood or urine to see if a woman is pregnant. HCG may also be measured to see if cancer of the ovaries or testicles is present.

Normal

These numbers are just a guide. The range for "normal" varies from lab to lab. Your lab may have a different range. Your lab report should show what range your lab uses for "normal." Also, your doctor will evaluate your results based on your health and other factors. So a number that is outside the normal range here may still be normal for you.

**Human chorionic gonadotropin (hCG) levels in blood** ^{footnote 2}
Men and nonpregnant women:	Less than 5 international units per liter (IU/L)
Pregnant women, 1 week of gestation (about 3 weeks after the last menstrual period):	5-50 IU/L
Pregnant women, 2 weeks of gestation (about 4 weeks after the LMP):	50-500 IU/L
Pregnant women, 3 weeks of gestation (about 5 weeks after the LMP):	100-10,000 IU/L
Pregnant women, 4 weeks of gestation (about 6 weeks after the LMP):	1080-30,000 IU/L
Pregnant women, 6-8 weeks of gestation (about 8-10 weeks after the LMP):	3500-115,000 IU/L
Pregnant women, 12 weeks of gestation (about 14 weeks after the LMP):	12,000-270,000 IU/L
Pregnant women, 13-16 weeks of gestation (about 15-18 weeks after the LMP):	Up to 200,000 IU/L

hCG levels in urine
Men:	None (negative test)
Nonpregnant women:	None (negative test)
Pregnant women:	Detectable (positive test)

High values

If you are pregnant, very high levels of hCG can mean a multiple pregnancy (such as twins or triplets). It can also mean a molar pregnancy or Down syndrome. You may also be further along in an early pregnancy than you thought, based on your last menstrual period.
In a man or a nonpregnant woman, a high hCG level can be a sign of a tumor (cancerous or noncancerous). These tumors can develop from a sperm or egg cell (germ cell tumor), such as a tumor of the testicles or ovaries. It may also mean some types of cancer, such as cancer of the stomach, pancreas, large intestine, liver, or lung.

Low values

If you are pregnant, a low level of hCG can mean an ectopic pregnancy or a miscarriage. It may also mean that you aren't as far along in an early pregnancy as you thought, based on your last menstrual period (LMP).
If you are pregnant, levels of hCG that are going down abnormally can mean a miscarriage (spontaneous abortion) is very likely.

What Affects the Test

You may not be able to have the test, or the results may not be helpful, if:

You do your urine test for hCG very early in pregnancy (during the first week after implantation) or on a urine sample taken in the middle of the day. The test may not always show an early pregnancy.
You have had a miscarriage (spontaneous abortion) or therapeutic abortion. HCG results may stay high (positive) for up to 4 weeks after a miscarriage or therapeutic abortion.
You got an injection of hCG to treat infertility. This may cause test results to appear high for several days after the injection.
There is blood in the urine sample or soap in the collecting container. These can change the hCG level.
You use diuretics or promethazine. These medicines can cause false low hCG levels in urine test results.
You use heparin, a medicine to prevent blood from clotting (anticoagulant).
You use certain medicines. These include hypnotics (such as Ambien), antipsychotics, and antinausea medicines (such as prochlorperazine). Be sure to tell your doctor what medicines you take.

What To Think About

Home pregnancy tests that find hCG in urine are easy to find and buy. To learn more, see the topic Home Pregnancy Tests.
A blood test for hCG is generally more accurate than a urine test. If you still think you're pregnant even after your urine test results do not show a pregnancy (negative results), you can try a blood test. Or you can repeat the urine test in a week.
A normal hCG value does not rule out the possibility of a tumor in the uterus, ovaries, or testicles. HCG is only one part of a group of tests when a tumor is suspected.

References

Citations

American College of Obstetricians and Gynecologists (2007, reaffirmed 2008). Screening for fetal chromosomal abnormalities. ACOG Practice Bulletin No. 77. Obstetrics and Gynecology, 109(1): 217-227.

Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Other Works Consulted

Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

Wapner RJ, et al. (2009). Prenatal diagnosis of congenital disorders. In RK Creasy et al., eds., Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice, 6th ed., pp. 221-274. Philadelphia: Saunders Elsevier.

Credits

ByHealthwise Staff
Primary Medical Reviewer Sarah A. Marshall, MD - Family Medicine
E. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine
Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Rebecca Sue Uranga, MD - Obstetrics and Gynecology

Current as ofNovember 21, 2017