Alpha fetoprotein
Fetal 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.
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Alpha fetoprotein (AFP) is a protein produced by the liver and yolk sac of a fetus. AFP has no normal function in adults. The alpha fetoprotein test (AFP) is a blood test performed to measure, diagnose, or monitor fetal distress or fetal abnormalities. It can also detect some liver disorders and some cancers in adults. During pregnancy, this test, along with the examination of amniotic fluid (amniocentesis), can help detect fetal spinal bifida or other defects of the fetus' neural tube.
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.
Normal Results
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:
- Cancer in testes, ovaries, biliary (liver secretion) tract, stomach, or pancreas
- Cirrhosis of the liver
- Liver cancer
- Malignant teratoma
- Recovery from hepatitis
- Problems during pregnancy
References
Driscoll DA, Simpson JL. Genetic screening and diagnosis. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 10.
Dugoff L, Wapner RJ. Prenatal diagnosis of congenital disorders. In: Lockwood CJ, Copel JA, Dugoff L et al, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2023:chap 30.
Lee E. Neonatology. In: Anderson CC, Kapoor S, Mark TE, eds. The Harriet Lane Handbook. 23rd ed. Philadelphia, PA: Elsevier; 2024:chap 18.
Lee P, Jain S, Pincus MR, et al. Diagnosis and management of cancer using serologic and other body fluid markers. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 76.
Version Info
Last reviewed on: 8/23/2023
Reviewed by: LaQuita Martinez, MD, Department of Obstetrics and Gynecology, Emory Johns Creek Hospital, Alpharetta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
