What is an alpha-fetoprotein test?
The alpha-fetoprotein (AFP) test is a blood test for pregnant people. Healthcare providers use the AFP test to check a fetus’s risks of birth defects or genetic conditions.
The AFP test measures alpha-fetoprotein levels. Alpha-fetoprotein is a protein that develops in the liver of a fetus. Irregular AFP levels in pregnant people can be a sign of a genetic disorder or birth defect (congenital disability).
What is the AFP tumor marker test?
Most commonly, healthcare providers use AFP tests in a pregnant person. But in some cases, your healthcare provider might order an AFP tumor marker test when you’re not pregnant. The tumor marker test has different purposes than the AFP test for pregnant people.
Newborn babies typically have high AFP levels that drop to low ranges by age 1. In an adult, high AFP may point to:
- Cirrhosis.
- Hepatitis A, hepatitis B or hepatitis C.
- Liver cancer.
- Ovarian or testicular cancer.
- Toxic hepatitis or autoimmune hepatitis.
Healthcare providers may also use AFP tumor marker tests to plan cancer treatment. For example, if you have high AFP levels and liver cancer, targeting cancer cells with specific drugs (targeted therapy) may be an effective treatment.
It’s important to understand that AFP tumor marker tests are simply tools to measure AFP levels. They can help diagnose cancer or other conditions. But an irregular test result doesn’t necessarily mean there’s a problem. Usually, your provider will order follow-up tests to learn more.
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When is the AFP test performed in pregnancy?
Pregnant people typically have the AFP test between 16 and 22 weeks of pregnancy.
All pregnant people should get the AFP test, but your healthcare provider may especially recommend it if you:
- Are older than 35.
- Have a family history of birth defects.
- Have diabetes.
What does the AFP test check for?
The test may detect:
- Genetic disorders, such as Down syndrome or Turner syndrome.
- Incorrect due dates.
- Multiples, such as twins or triplets.
- Neural tube defects, such as spina bifida or anencephaly.
