Alpha Fetoprotein (AFP), Serum

Key Aspects of AFP

• Purpose: The protein is essential for fetal development. In non-pregnant adults, AFP levels are normally very low, typically under 10–15 ng/mL.
• Tumor Marker (Adults): Elevated AFP is a strong indicator of hepatocellular carcinoma (liver cancer) or germ cell tumors (testicular or ovarian). It is used to screen high-risk patients (e.g., those with chronic hepatitis or cirrhosis).
• Prenatal Screening: The maternal serum AFP test is conducted between 15 and 20 weeks of pregnancy to check for fetal abnormalities, including neural tube defects (high levels) and Down syndrome (low levels).

Conditions Associated with Abnormal Levels

• Elevated AFP: Liver cancer (hepatocellular carcinoma), hepatitis, cirrhosis, and certain testicular cancers (nonseminomatous germ cell tumors).
• Abnormal Pregnancy Levels: Neural tube defects (like spina bifida), Down syndrome, or inaccuracies in calculated gestational age.

Limitations

• Not a Diagnostic Tool: An AFP test alone cannot confirm cancer; it is usually followed by imaging tests (like CT or MRI) or a liver biopsy.
• False Positives: Non-cancerous liver conditions like hepatitis or cirrhosis can cause elevated AFP levels.

Common Uses

• AFP-L3% Test: This specialized test compares a specific form of AFP (AFP-L3) to the total amount to specifically evaluate liver cancer risk.
• Monitoring Cancer Treatment: Levels are tracked to see if a tumor is responding to treatment or if it has returned.