AFP
Also known as: Alpha-Fetoprotein
What Does AFP Measure?
Alpha-Fetoprotein (AFP) is a protein primarily produced by the liver and yolk sac of a developing fetus. In adults, AFP is measured in the blood to detect abnormally elevated levels that may indicate certain medical conditions. The test quantifies the concentration of this fetal protein circulating in the bloodstream, typically expressed in nanograms per milliliter (ng/mL) or international units per milliliter (IU/mL).
Why Does AFP Matter?
AFP is a critical tumor marker used to help diagnose and monitor liver cancer (hepatocellular carcinoma) and certain germ cell tumors such as testicular and ovarian cancers. In pregnant women, AFP levels are measured as part of prenatal screening to assess the risk of neural tube defects like spina bifida, chromosomal abnormalities such as Down syndrome, and abdominal wall defects in the fetus. Monitoring AFP levels over time also helps clinicians evaluate treatment response, detect cancer recurrence, and assess liver disease progression in high-risk individuals.
Normal Ranges
Males
Less than 10 ng/mL (or <7 IU/mL) for adult males
Females
Less than 10 ng/mL (non-pregnant); 10–150 ng/mL in early pregnancy, rising to 10–150,000 ng/mL near term
Children
Varies by age; newborns may have levels up to 100,000 ng/mL, declining to adult levels by 8–12 months
Causes of High Levels
- Hepatocellular carcinoma (primary liver cancer) — often causes markedly elevated AFP above 400 ng/mL
- Germ cell tumors of the testes or ovaries (e.g., yolk sac tumors, non-seminomatous testicular cancer)
- Liver cirrhosis or chronic active hepatitis due to regenerative liver activity
- Hepatitis B or C infection causing significant liver inflammation and damage
- Gastric, pancreatic, or colorectal cancers that metastasize to the liver
- Normal pregnancy, particularly in the second trimester when maternal serum AFP peaks
Causes of Low Levels
- Chromosomal abnormalities in the fetus such as Down syndrome (trisomy 21) or trisomy 18, which are associated with lower maternal serum AFP
- Gestational diabetes in the mother, which may suppress AFP production
How to Improve Your AFP
Diet
- Maintain a liver-healthy diet rich in fruits, vegetables, and whole grains to support liver function and reduce inflammation
- Limit alcohol consumption, as chronic alcohol use damages the liver and can elevate AFP through cirrhosis
- Reduce intake of aflatoxin-contaminated foods (e.g., moldy peanuts, corn) since aflatoxin is a known liver carcinogen linked to elevated AFP
- Increase cruciferous vegetables like broccoli and Brussels sprouts, which contain compounds supporting liver detoxification
- Choose lean proteins and limit red and processed meats to reduce liver stress and cancer risk
Supplements
- Milk thistle (silymarin) 140–420 mg/day may support liver cell protection and reduce inflammation (consult a physician first)
- Vitamin D 1,000–2,000 IU/day has been associated with reduced hepatocellular carcinoma risk in deficient individuals
- Omega-3 fatty acids 1,000–2,000 mg/day EPA+DHA may help reduce liver inflammation associated with chronic liver disease
- N-acetylcysteine (NAC) 600–1,200 mg/day may support liver detoxification and antioxidant capacity (under medical supervision)
Related Biomarkers
Frequently Asked Questions
What does a high AFP level mean?
A high AFP level in a non-pregnant adult can be a warning sign of liver cancer (hepatocellular carcinoma), testicular cancer, or ovarian germ cell tumors. However, elevated AFP can also occur with benign liver conditions like cirrhosis or hepatitis. A single elevated result does not confirm cancer — your doctor will likely order imaging tests and monitor AFP levels over time to determine the cause.
Is AFP testing only used for cancer?
No. AFP is used in two main clinical contexts: as a tumor marker in adults to detect or monitor liver and germ cell cancers, and as a prenatal screening tool in pregnant women. During pregnancy, maternal serum AFP is measured between 15–20 weeks of gestation to screen for neural tube defects, Down syndrome, and other fetal abnormalities. The interpretation differs significantly between these two uses.
What AFP level is considered dangerous or indicative of cancer?
In adults, AFP levels above 400 ng/mL are strongly associated with hepatocellular carcinoma, especially when combined with liver imaging findings. However, levels above 10 ng/mL in a non-pregnant adult warrant further investigation. Some liver cancers may produce only modestly elevated AFP, while very high levels (thousands of ng/mL) are more definitively suggestive of malignancy. Clinical context, imaging, and biopsy are used together for diagnosis.
Can AFP levels return to normal after treatment?
Yes. If AFP is elevated due to cancer, successful treatment — such as surgery, chemotherapy, or ablation — typically causes AFP levels to fall, sometimes back to the normal range. This is why AFP is used to monitor treatment response. A rising AFP after treatment may indicate cancer recurrence before it is visible on imaging, making it a valuable early warning tool during follow-up care.