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Blood test
Blood test

Alpha fetoprotein
Definition:
A test that measures the amount of alpha fetoprotein (AFP) in serum (blood).
Alternative Names:
Fetal alpha globulin; AFP
How the test is performed:
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test:
Adult:
There is no special preparation.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

How the test will 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.
Why the test is performed:

AFP is a protein normally produced by the liver and yolk sac of a fetus. AFP levels decrease soon after birth; AFP probably has no normal function in adults.

AFP is measured to:

  • diagnose or monitor fetal distress or fetal abnormalities
  • diagnose some liver disorders
  • screen for and monitor some cancers.

During pregnancy, this test, along with the examination of amniotic fluid (amniocentesis), can help detect fetal spina bifida or other defects of the fetus' neural tube associated with elevated levels of AFP.
Normal Values:
Males or nonpregnant females: less than 10 micrograms/milliliter
What abnormal results mean:
Greater-than-normal levels of AFP may indicate: During pregnancy, increased levels of AFP may indicate: Additional conditions under which the test may be performed:

What the risks are:
  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins
Special considerations:
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.
Review Date: 2/17/2002
Reviewed By: Michael C. Milone, M.D., Ph.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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