Alpha-fetoprotein (AFP) levels
Alpha-fetoprotein (AFP) is a protein primarily produced by the liver and fetal tissue during growth and development. AFP levels are measured through a tumor marker test that detects total AFP in serum or plasma and is mainly used to identify and monitor certain cancers, including those of the liver, testes, and ovaries. This test can be particularly important for patients with chronic liver disease due to their elevated risk of liver cancer.
Pregnant women also exhibit higher AFP levels, but in this context, the test is employed to assess potential fetal abnormalities rather than cancer detection. The procedure involves drawing a small blood sample, typically without the need for special preparation, and carries minimal risks such as bruising or fainting. Results can vary based on sex, age, and the laboratory conducting the test. Elevated AFP levels can indicate the presence of tumors, with higher levels suggesting larger tumors, though the test is not definitive for diagnosis. In some cases, additional testing and imaging may be required to confirm any findings.
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Alpha-fetoprotein (AFP) levels
ALSO KNOWN AS: Total AFP, AFP-13 percent, alpha-fetoglobulin, αFP, AFP tumor marker
DEFINITION: Alpha fetoprotein (AFP) is a protein produced by the liver during cell growth and division. It is most commonly made by fetal tissue, but it can also be produced by cancer cells or by normal cells in response to cancer. The tumor marker test for AFP generally measures total AFP. The test is performed on serum or plasma on an automated chemistry analyzer.
Cancers diagnosed: Cancers of the liver, testes, and ovaries
Why performed: The AFP tumor marker test is done to detect and monitor cancers of the liver, testes, and ovaries. Physicians may order the test for patients with chronic liver disease because of the high risk of developing liver cancer. Because AFP is also produced by a fetus, AFP levels are generally higher in pregnant women. A test for AFP done on pregnant women is not done to detect a tumor but is used with other data to detect possible abnormalities in the developing fetus.
Patient preparation: No special preparation is necessary.
Steps of the procedure: A small sample of blood is collected from a vein and placed in a tube. In children, blood may be obtained from a capillary in the heel or finger.
After the procedure: A small gauze or cotton ball is applied at the site of needle insertion. The patient is asked to apply pressure. The person collecting the blood observes the site for bleeding and may apply a bandage. The bandage may usually be removed in thirty to sixty minutes.
Risks: Risks include bleeding, bruising, hematoma (bleeding under the skin), fainting, light-headedness, or the need for multiple needle sticks to obtain a sample.
Results: Normal AFP levels vary by the patient’s sex and age and by the analyzer used. Each laboratory establishes normal ranges based on this information. The physician receives a report of the test results with the normal values established by the testing laboratory.
AFP decreases at birth, and adult levels are normally low. Elevated levels are present in people who are pregnant, but levels can also be elevated in people with liver cancer and in some testicular and ovarian cancers. Generally, higher levels of AFP indicate a larger tumor. The test is not considered specific for diagnosis, but it is an indicator that a tumor may be present. Physicians may order imaging studies and additional laboratory tests to determine the presence of a tumor. Some physicians order a test called AFP-13 percent, as 13 is one of the forms of AFP that make up the total. An increased percentage of AFP-13 to total AFP indicates an increased risk of developing liver cancer or a poorer prognosis. AFP levels usually return to normal within a month of treatment.
Bibliography
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