Alpha-Fetoprotein (AFP): Role, Testing, and Results

What Is Alpha-Fetoprotein?

Alpha-fetoprotein is a protein made primarily by the liver of a developing fetus. In adults, AFP levels are normally low but can rise due to certain medical conditions.

AFP plays a key role in fetal development, helping to transport various substances like hormones and fatty acids. However, its importance in adults lies mainly in its use as a biomarker.

Doctors often measure AFP to help diagnose and monitor specific conditions such as:

• Liver diseases like hepatocellular carcinoma
• Germ cell tumors
• Certain birth defects during pregnancy

By tracking AFP levels, healthcare providers can detect abnormal changes in the body, guide further testing, and evaluate treatment effectiveness.

When Is Alpha-Fetoprotein Testing Recommended?

The AFP test is done to help diagnose or monitor various health conditions in both adults and pregnant women.

Your doctor may recommend an AFP test if:

• You are pregnant and undergoing routine prenatal screening
• You are at high risk for liver cancer due to hepatitis B or cirrhosis
• You have a known liver mass or tumor
• You are being treated for liver cancer or a germ cell tumor and need monitoring
• Your doctor suspects a testicular or ovarian tumor
• You had previous abnormal results on prenatal screenings

How Is Alpha-Fetoprotein Testing Conducted?

AFP is measured using a simple blood test. A healthcare professional draws a sample from a vein, usually in the arm.

Types of Tests That May Include AFP:

• Maternal Serum Triple or Quad Screen during pregnancy
• Tumor Marker Panels for liver or testicular cancer
• AFP-L3 Test, a specific subtype to evaluate liver cancer risk

Special Preparations:

• Non-pregnant individuals: Usually, no special preparation is needed. Eating and drinking normally is allowed.
• Pregnant individuals: The test is time-sensitive and usually done between 15 and 20 weeks of pregnancy.

Inform your doctor about any medications or supplements you’re taking.

What Are the Normal Alpha-Fetoprotein Levels?

• Adults (non-pregnant): Less than 10 ng/mL
• Pregnancy (second trimester): 10-150 ng/mL (levels vary by gestational age)

Note: The units of measurement and the normal ranges can differ depending on the laboratory and the specific methods used.

What Do Abnormal Levels Mean?

Alpha-Fetoprotein High Levels

High AFP levels can be a sign of certain conditions in both pregnant and non-pregnant individuals.

Possible Causes:

• Liver cancer (Hepatocellular carcinoma): AFP often rises in this type of cancer.
• Testicular or ovarian tumors: Some germ cell tumors release AFP.
• Chronic liver diseases: Hepatitis and cirrhosis may cause mildly elevated levels.
• Pregnancy-related issues:
  • Neural tube defects (e.g., spina bifida)
  • Underestimated gestational age
  • Multiple pregnancies (twins or more)

• Follow up with imaging tests like ultrasound or MRI to find the source.
• Repeat the AFP test over time to monitor trends.
• Discuss with a specialist if liver or reproductive organ cancer is suspected.
• Pregnant women may be referred for additional screenings like amniocentesis.

Alpha-Fetoprotein Low Levels

Low levels of AFP are mostly relevant during pregnancy, where they may suggest certain genetic concerns.

Possible Causes:

• Down syndrome (Trisomy 21): AFP tends to be lower than expected.
• Edwards syndrome (Trisomy 18): Also associated with reduced AFP levels.
• Incorrect gestational age: Overestimating the baby's age can make AFP levels appear too low.

• Schedule additional prenatal tests like cell-free DNA testing or amniocentesis.
• Recheck gestational age through ultrasound.
• Meet with a genetic counselor for deeper evaluation.

Which Specialist Should You Consult?

Depending on the suspected condition related to abnormal AFP levels, you may need to consult:

• Oncologist - if cancer is suspected or being monitored
• Hepatologist - for liver disease and cirrhosis
• Obstetrician or Maternal-Fetal Medicine Specialist - for abnormal AFP levels during pregnancy
• Genetic Counselor - for fetal development or inherited condition concerns