Summary
Alpha-Fetoprotein (AFP) is a protein produced in large amounts during fetal development and at low levels in adults. A raised AFP in adults is most associated with primary liver cancer (hepatocellular carcinoma) and certain testicular and ovarian germ cell tumours. AFP is used for surveillance in people at high risk of liver cancer, and for diagnosis and monitoring of these specific cancers.
In adults, AFP is normally low. It can rise significantly in hepatocellular carcinoma (HCC) — the main type of primary liver cancer — and in non-seminomatous germ cell tumours of the testes or ovaries. It can also be modestly raised in benign liver conditions such as hepatitis and cirrhosis, and during pregnancy.
In people with chronic liver disease or cirrhosis, who are at increased risk of liver cancer, AFP is used alongside ultrasound for surveillance. A rising or markedly elevated AFP prompts further imaging.
In germ cell tumours, AFP (with beta-hCG and LDH) helps with diagnosis, risk stratification, and monitoring treatment response. Falling levels after treatment indicate response; rising levels suggest recurrence.
What It Is
AFP is a glycoprotein synthesised by the fetal yolk sac and liver, structurally related to albumin. After birth its production falls rapidly, so adult levels are low. Re-expression occurs in certain malignancies, notably hepatocellular carcinoma and yolk-sac-containing germ cell tumours.
AFP is used both diagnostically and for monitoring. In HCC surveillance among high-risk patients (cirrhosis, chronic hepatitis B/C), AFP complements imaging, though it is not sensitive or specific enough to be used alone. In germ cell tumours it forms part of the marker panel with beta-hCG and LDH and is essential for staging and follow-up.
Reference ranges: approximately < 10 ng/mL in non-pregnant adults, varying by laboratory. Very high levels strongly suggest malignancy, while modest elevations can occur with benign liver disease.
Functions
Liver cancer surveillance
Used with ultrasound to monitor people at high risk of hepatocellular carcinoma, such as those with cirrhosis.
Germ cell tumour marker
Part of the marker panel (with beta-hCG and LDH) for diagnosing and monitoring testicular and ovarian germ cell tumours.
Treatment monitoring
Falling AFP indicates response to treatment; rising AFP suggests recurrence.
Prognostic information
Very high AFP levels can indicate more advanced disease and inform prognosis.
Reference Ranges
Alpha-Fetoprotein (AFP)
Measured in ng/mL| Status | Range (ng/mL) | Range (kU/L) | What it means |
|---|---|---|---|
| Normal | < 10 | < 10 | Normal adult AFP — no evidence of AFP-producing tumour (cancer not fully excluded). |
| Mildly raised | 10–100 | 10–100 | Mild elevation — often benign liver disease; monitor and investigate as indicated. |
| Elevated | 100–400 | 100–400 | Significant elevation — raises suspicion of liver or germ cell cancer; investigate. |
| Markedly high | > 400 | > 400 | Very high — strongly suggestive of hepatocellular carcinoma or germ cell tumour. |
AFP is raised in pregnancy and can be mildly elevated in benign liver disease. It is not a general screening test. Reference ranges vary by laboratory. Interpret with imaging, other markers, and clinical context.
Symptoms of Imbalance
AFP causes no symptoms itself; elevation reflects an underlying liver condition or tumour.
- A normal AFP is reassuring but does not exclude cancer
- No symptoms from a low AFP
- Symptoms of liver cancer: abdominal pain, weight loss, jaundice
- Symptoms of chronic liver disease
- Testicular lump or swelling (germ cell tumour)
- Often no symptoms in early disease
Causes of Imbalance
- Normal in healthy non-pregnant adults
- Effective cancer treatment (falling AFP)
- Hepatocellular carcinoma (primary liver cancer)
- Non-seminomatous germ cell tumours (testicular, ovarian)
- Chronic hepatitis and cirrhosis (modest elevation)
- Pregnancy
- Benign liver regeneration after injury
FAQs
In a non-pregnant adult, a significantly raised AFP most often points to primary liver cancer (hepatocellular carcinoma) or certain testicular or ovarian germ cell tumours. Modest elevations can also occur with benign liver disease such as hepatitis and cirrhosis. The level, the trend over time, and accompanying imaging all help determine the cause, so AFP is always interpreted in context rather than alone.
AFP is not used to screen the general population, but it does have a role in surveillance for people at high risk of liver cancer — particularly those with cirrhosis or chronic hepatitis B or C. In this group, AFP is used together with regular ultrasound. On its own, AFP is not sensitive or specific enough, which is why imaging is the mainstay of surveillance.
AFP is produced by the developing baby and crosses into the mother’s blood, so levels rise naturally during pregnancy. Maternal AFP is in fact measured as part of prenatal screening for certain conditions. Because of this, AFP results in pregnant women are interpreted using pregnancy-specific reference ranges, and a raised AFP in pregnancy is expected rather than a sign of cancer.
In germ cell tumours of the testis, AFP is measured alongside beta-hCG and LDH. These markers help confirm the diagnosis, classify the tumour type, assess how advanced it is, and monitor the response to treatment. Falling AFP after treatment indicates the cancer is responding, while a rising level can signal recurrence — making AFP an important part of follow-up.
References
- Galle PR, et al. EASL clinical practice guidelines: management of hepatocellular carcinoma. J Hepatol. 2018;69(1):182–236. View source
- Gilligan TD, et al. American Society of Clinical Oncology clinical practice guideline on uses of serum tumor markers in adult males with germ cell tumors. J Clin Oncol. 2010;28(20):3388–3404. View source
- Sharma B, et al. Serum alpha-fetoprotein in hepatocellular carcinoma. World J Hepatol. 2015;7(15):1936–1949. View source