AFP Test: What It Is, How It Works & What the Results Mean

The AFP test, also known as the Alpha-Fetoprotein test, is an easy blood test that measures alpha-fetoprotein levels in your blood. Although AFP occurs naturally in a developing fetus, produced mainly by the yolk sac early in pregnancy and later by the fetal liver, adults normally have a low level of AFP. Still, certain health issues such as liver disease, cancers, and certain pregnancy-related factors can affect maternal serum AFP levels. 

This test is applied to various medical conditions. It is used extensively in prenatal screening, identifying defects in unborn babies. In adults, it is typically applied to monitor liver cancer, testicular cancer, and germ cell tumours and to support assessment and monitoring in people with chronic liver disease, especially when screening for hepatocellular carcinoma. Knowing about the AFP test, the results, and how these results indicate things can assist individuals and physicians in taking appropriate action towards diagnosis and treatment.

What Is the AFP Test?

The AFP (Alpha-Fetoprotein) test is a highly specific blood test that measures the level of protein concentration in blood. AFP is a glycoprotein or a protein with a carbohydrate attached to it. In fetal development, AFP is critical for the transport of nutrients and for the protection of the developing baby. In adults, though, high levels of AFP can indicate underlying medical conditions, especially those involving the liver or reproductive system.

Uses in Medicine

Prenatal Screening

Physicians prescribe the AFP test for pregnant women, typically as part of a combined screening panel such as the Triple Marker test (AFP + hCG + Estriol) or Quad Screen (AFP + hCG + Estriol + Inhibin A), which assess the risk of neural tube defects and chromosomal abnormalities such as Down syndrome and Edwards syndrome. 

Read More about Types of High-Risk Pregnancies and Their Management

Cancer Monitoring

AFP is also regarded as a tumour marker in that elevated levels can be associated with the occurrence of liver cancer (hepatocellular carcinoma), testicular cancer, or ovarian cancer. It is both utilised for the initial diagnosis and for assessing the progress of treatment.

Liver Disease

For individuals with chronic liver diseases like hepatitis, cirrhosis, or fatty liver disease, an AFP test can be conducted to check liver cell injury. Nevertheless, a high level of AFP alone is not sufficient for a diagnosis and typically requires additional testing.

How Does the AFP Test Works?

The Test Procedure:

The Alpha-Fetoprotein (AFP) test is a simple blood test that involves collecting a small sample of blood from a vein in your arm. A healthcare professional will clean the area, gently insert a needle, and collect the blood in a vial for laboratory analysis. The procedure usually takes less than five minutes and does not require fasting or any specific dietary changes. You may experience slight discomfort during the needle insertion, followed by mild soreness or bruising at the injection site.

Test Variations:

• During Pregnancy: The AFP test is generally performed between the 15th and 20th weeks of pregnancy to assess the risk of certain birth defects, including neural tube defects. It can be conducted as an individual screening test or combined with other blood tests as part of a triple or quad screening.
• For Adults: In non-pregnant adults, the AFP test is primarily used as a tumour marker to help monitor certain medical conditions, particularly liver cancer and some testicular or ovarian germ cell tumours. It may also help assess liver-related conditions. Doctors interpret AFP levels alongside medical history, physical examinations, imaging tests, and other diagnostic investigations.

What Do The Results Mean?

Normal AFP Levels

• Pregnant Women: Normal AFP levels vary depending on the stage of pregnancy and are interpreted along with other prenatal tests.
• Adults: Reference ranges may slightly vary depending on the laboratory.

Elevated AFP Levels

• During Pregnancy: Increased AFP levels during pregnancy might point to potential neural tube defects (such as spina bifida) or defects of the abdominal wall in the fetus. But increased levels can also occur when having twins or triplets or with an error in pregnancy dating.
• Cancer & Liver Disease: In adults, high AFP levels may be seen in patients with liver cancer, testicular cancer, ovarian cancer, or long-standing liver diseases such as hepatitis or cirrhosis. More testing is needed to diagnose, though.

Low AFP Levels

• In Pregnancy: As part of combined screening low AFP levels may suggest a lower risk of birth defects but could also indicate conditions like Down syndrome or trisomy 18.
• In Adults: Low AFP levels are generally not a concern unless other abnormal test results accompany them.

Factors That Can Affect AFP Results

Pregnancy Factors

• Carrying multiple babies (twins, triplets) can cause higher-than-normal AFP levels.
• Pregnancy complications like placental issues or preterm labour may also affect AFP test results.

Health Conditions

• Chronic liver diseases like cirrhosis and hepatitis can result in mildly elevated AFP levels.
• Certain medications or treatments (including chemotherapy) can change AFP levels over time, which is why results are interpreted in a clinical context.

False Positives & Negatives

• False Positives: High AFP levels do not always indicate cancer or birth defects. Additional tests, such as ultrasounds, imaging scans, or genetic testing, are required for confirmation.
• False Negatives: A normal AFP result does not always rule out conditions like liver cancer or birth defects, so doctors may recommend further testing.

Conclusion

The AFP test is a valuable tool used in prenatal care, cancer detection, and liver disease monitoring. However, it is not a standalone diagnostic test. It should always be interpreted alongside other medical evaluations and patient history.

At Nanavati Max Super Speciality Hospital, we offer comprehensive screening and diagnostic services to make sure you receive accurate test results and expert medical guidance. If you have concerns about your AFP levels, book an appointment with our specialists todays.

Frequently Asked Questions

1. What is a normal AFP level during pregnancy?

Normal AFP levels vary by pregnancy stage. Your doctor will compare your levels with expected values and may recommend additional tests if needed.

2. Can AFP levels indicate a risk of liver cancer?

Yes, elevated AFP levels can be a sign of liver cancer, particularly in people with chronic liver disease. However, further testing is needed for confirmation.

3. Is the AFP test only for pregnant women?

No, the AFP test is also used in adults to detect liver cancer, testicular cancer, and other conditions.

4. What should I do if my AFP levels are high?

A high AFP level doesn’t always mean something is wrong, but it does require further evaluation. Consult your doctor for additional tests.

5. Can medications affect AFP test results?

Yes, certain medications, including chemotherapy drugs, may impact AFP levels. Inform your doctor about any medications you are taking.

6. How accurate is the AFP test in detecting cancer?

The AFP test alone cannot diagnose cancer, but it helps doctors monitor cancer progression and treatment effectiveness when used alongside imaging tests.