Alpha-Fetoprotein (AFP) in Blood
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 developing baby (fetus). The amount of AFP in the blood of a pregnant woman can help find certain problems with her baby.
Normal
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. 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 Reference ultrasound Opens New Window may be done to check the baby's age more accurately.
| Men and nonpregnant women: |
0–40 Reference nanograms per milliliter (ng/mL) Opens New Window or Reference micrograms per liter (mcg/L) Opens New WindowReference 2 |
|---|---|
| Women 15–18 weeks pregnant: |
10-150 ng/mL or mcg/LReference 3 |
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 Reference diabetes Opens New Window that needs injections of Reference insulin Opens New Window; 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. 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
- In a pregnant woman, high alpha-fetoprotein values 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, high alpha-fetoprotein values can mean:
- Cancer of the liver, testicles, or ovaries is present.
- Liver disease, such as Reference cirrhosis Opens New Window or Reference hepatitis Opens New Window, is present.
- Reference Alcohol abuse Opens New Window 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 may have Reference Down syndrome Opens New Window.
In a nonpregnant adult, alpha-fetoprotein is not normally present.
| By: | Reference Healthwise Staff | Last Revised: Reference April 4, 2012 |
| Medical Review: | Reference Sarah Marshall, MD - Family Medicine
Reference Siobhan M. Dolan, MD, MPH - Reproductive Genetics |
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This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.
