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AFP Tumor Markers

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Also known as: AFP; Total AFP; AFP-L3%
Formal name: Alpha-fetoprotein, Total; Alpha-fetoprotein-L3 Percent

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Were you looking instead for AFP Maternal, ordered during pregnancy?

The Test Sample

What is being tested?

Alpha-fetoprotein (AFP) is a protein produced primarily by the liver in a developing baby (fetus) and the portion of a developing embryo that is similar to the yolk cavity in bird eggs (yolk sac tissues). AFP levels are typically elevated when a baby is born and then decline rapidly. Liver damage and certain cancers can increase AFP concentrations significantly. This test measures the level of AFP in the blood.

AFP is produced whenever liver cells are regenerating. With chronic liver diseases, such as hepatitis and cirrhosis, AFP may be chronically elevated. Very high concentrations of AFP may be produced by certain tumors. This characteristic makes the AFP test useful as a tumor marker. Increased amounts of AFP are found in many people with a type of liver cancer called hepatocellular carcinoma and in a liver cancer occurring in infants called hepatoblastoma. They are also found in some people with cancers of the testicles or ovaries.

AFP exists in several different variants. The standard AFP test is for a total AFP, one that measures all of the AFP variants together. This is the primary AFP test used in the United States.

One of the AFP variants is called L3 because of its ability, in the laboratory, to bind to a particular protein called Lens culinaris agglutinin. The AFP-L3% test is a relatively new test that compares the amount of AFP-L3 to the total amount of AFP. An increase in the percentage of L3 is associated with increased risk of developing hepatocellular carcinoma in the near future and of having a poorer prognosis, as the L3-related cancers tend to be more aggressive.

Among patients with low total AFP, AFP-L3 can be higher in those with hepatocellular carcinoma than patients with benign liver diseases. Tumor markers including total AFP and AFP-L3 are used in addition to ultrasound for surveillance of hepatocellular carcinoma in Japan. This practice is different from that in the U.S. and Europe, but the two tests are occasionally ordered by healthcare practitioners in the U.S.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.