Alpha fetoproteinFetal alpha globulin; AFP
Alpha fetoprotein (AFP) is a protein produced by the liver and yolk sac of a developing baby during pregnancy. AFP levels go down soon after birth. It is likely that AFP has no normal function in adults.
A test can be done to measure the amount of AFP in your blood.
How the Test is Performed
A blood sample is needed. Most of the time, blood is typically drawn from a vein located on the inside of the elbow or the back of the hand.
How to Prepare for the Test
You do not need to take any special steps to prepare.
How the Test will Feel
You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
Why the Test is Performed
Your health care provider may order this test to:
- Screen for problems in the baby during pregnancy. (The test is done as part of a larger set of blood tests called quadruple screen.)
- Diagnose certain liver disorders.
- Screen for and monitor some cancers.
The normal values in males or nonpregnant females is generally less than 40 micrograms/liter.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Greater than normal levels of AFP may be due to:
Driscoll DA, Simpson JL, Holzgreve W, Otano L. Genetic screening and prenatal genetic disgnosis. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem Pregnancies. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 10.
Fundora J. Neonatology. In: Hughes HK, Kahl LK, eds. The Johns Hopkins Hospital: The Harriet Lane Handbook. 21st ed. Philadelphia, PA: Elsevier; 2018:chap 18.
Wapner RJ. Prenatal diagnosis of congenital disorders. In: Creasy RK, Resnik R, Iams JD, Lockwood CJ, Moore TR, Greene MF, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 30.