Alpha fetoprotein

Alternative Names: Fetal alpha globulin; AFP

Alpha fetoprotein (AFP) is a protein normally produced by the liver and yolk sac of a developing baby during pregnancy. AFP levels decrease soon after birth. AFP probably has no normal function in adults.

A test can be done to measure the amount of AFP in your blood.

See also: Quadruple screen

Why is the Test Performed?

Your doctor may order this test to:

• Screen for problems in the baby during pregnancy
• Diagnose certain liver disorders
• Screen for and monitor some cancers

During pregnancy, this AFP test can be done along with amniocentesis to help detect spina bifida or other birth defects in the developing baby.

How is the Test Performed?

A blood sample is needed. For information on how this is done, see: Venipuncture

Preparation for the Test

There is no special preparation.

How will the Test Feel?

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Alpha fetoprotein Risks

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Normal Results for Alpha fetoprotein

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 doctor 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

During pregnancy, abnormal levels of AFP (as part of a quadruple screen) may be due to:

• Birth defects, including:
  • Anencephaly
  • Duodenal atresia
  • Gastroschisis
  • Omphalocele
  • Spina bifida
  • Tetralogy of Fallot
  • Turner syndrome
• Genetic disorders, including Down syndrome
• Inaccurate due date
• Intrauterine death (usually results in a miscarriage)
• Multiple pregnancy (twins, triplets, etc.)

Blood test	Alpha fetoprotein - series

Review Date: 9/12/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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