Alpha-Fetoprotein (AFP) In Blood: Results

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Results

An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of a unborn baby (fetus). The amount of AFP in the blood of a pregnant woman can help find certain problems with her baby.

Normal

Normal AFP values may vary from lab to lab. Also, normal values vary with the age of the baby; a high or low AFP may mean that the age of the baby has been recorded wrong or not calculated correctly. An ultrasound may be done to check the baby's age more accurately.

In pregnant women, the amount of AFP gradually rises starting in the 14th week of pregnancy. It continues to rise until a month or two before giving birth, then it slowly decreases. Values are generally slightly higher for black women than they are for white women. Values are slightly lower for Asian women than they are for white women. An accurate estimate of the age of the baby is needed to understand the AFP value correctly.

The normal range of AFP values is adjusted for each woman's age, weight, and race; whether she has diabetes that needs injections of insulin; and the age of her baby (gestational age). If the age of the baby is changed after an ultrasound, the AFP must then be adjusted as well. The middle of this adjusted range is called the multiple of median (MoM). An AFP value that is 0.5 to 2.5 times the MoM value is considered normal for that woman. Each woman and her doctor need to look at the range of AFP values that is normal for her when she has an AFP test.

High values

• High alpha-fetoprotein values in a pregnant woman can mean:
  • The age (gestational age) of the baby is wrong.
  • The woman is pregnant with more than one baby, such as twins or triplets.
  • The baby has a neural tube defect.
  • The baby's intestines or other abdominal organs are outside the body (called an abdominal wall defect or omphalocele). Surgery after birth will be needed to correct the problem.
  • The baby is not alive.
• In a nonpregnant adult, a high alpha-fetoprotein value can mean:
  • Cancer of the liver, testicles, or ovaries is present.
  • Liver disease, such as cirrhosis or hepatitis, is present.
  • Alcohol abuse is present.

Low values

In a pregnant woman, a low level of alpha-fetoprotein can mean:

• The age (gestational age) of the baby is wrong.
• The baby has Down syndrome.

In a nonpregnant adult, alpha-fetoprotein is not normally present.

Last updated:	May 14, 2008
Author:	Sandy Jocoy, RN
Reviewed By:	Sarah Marshall, MD - Family Medicine, Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Editors:	Kathleen M. Ariss, MS, Tracy Landauer