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Research explainer · Tumor markers
Causes of High Alpha-Fetoprotein (AFP): Liver Disease, Cancer, Pregnancy and What Levels Mean
Alpha-fetoprotein (AFP) is one of the oldest tumor markers in medicine, and one of the most misunderstood. A high result can point to liver cancer or a germ cell tumor, but it is just as likely to reflect chronic hepatitis, cirrhosis, pregnancy or a baby’s normal development. This guide explains what AFP is, what raises it, how clinicians interpret a result, and where quantitative AFP fits in liver cancer surveillance.
At a glance
What AFP is
A protein made by the fetal liver and yolk sac; low in healthy adults
Typical adult level
Usually below about 8–10 ng/mL (laboratory-specific)
Main causes of high AFP
Liver disease, liver cancer, germ cell tumors, pregnancy, infancy
Key caution
Not diagnostic alone; about 30% of liver cancers have normal AFP
OncoFirm™ status
Quantitative AFP is a future pipeline candidate; not for sale
On this page
Key points
High AFP in brief
<8.4 ng/mLexample adult reference limit (Mayo Clinic Laboratories); ranges vary by lab
~70%of hepatocellular carcinomas raise AFP, so about 30% do not
~5 daysAFP half-life, which shapes how quickly levels fall after treatment
Figures are from the laboratory and guideline sources listed in the references.
Definition
What is alpha-fetoprotein?
Alpha-fetoprotein (AFP) is a glycoprotein made mainly by the fetal liver and yolk sac. It is the main blood protein of the fetus, much as albumin is in adults. After birth, production falls quickly, so healthy adults have very little AFP in their blood. A raised AFP signals that cells with fetal-like activity, regenerating liver cells or certain tumors, are making it again.
AFP is measured in serum or plasma in ng/mL (some laboratories report IU/mL). For the marker itself, see AFP (alpha-fetoprotein); for how tumor markers work in general, see what are cancer biomarkers?.
Normal levels
What counts as normal depends on age and pregnancy
AFP spans five orders of magnitude, from a few ng/mL in healthy adults to over 100,000 ng/mL in newborns and some tumors. The same number can be normal in one person and concerning in another.
- Newborns and infants: AFP is very high at birth (often above 100,000 ng/mL) and falls rapidly, reaching adult levels by about one year. Infant results must be read against age-specific ranges.
- Pregnancy: AFP from the fetus crosses into the mother's blood, so maternal serum AFP rises during pregnancy and is reported as a multiple of the median (MoM) for gestational age.
- Non-pregnant adults: usually below about 8–10 ng/mL, depending on the laboratory method.
Cause 1 · Liver
Liver disease and liver cancer
- Hepatocellular carcinoma (HCC). The most important cancer cause in adults. AFP is raised in roughly 70% of cases and can exceed 100,000 ng/mL, but around 30% of tumors, including many small early ones, do not raise it.
- Chronic hepatitis B or C and cirrhosis. Inflammation and regeneration often cause mild, fluctuating elevations, typically from just above normal to a few hundred ng/mL, which overlap with early cancer.
- Liver regeneration after injury. Recovery from acute hepatitis or drug-induced injury can raise AFP temporarily as new liver cells grow.
- Hepatoblastoma. The most common liver cancer in young children, usually with markedly raised AFP.
- Liver metastases. Occasionally associated with modest increases, depending on the primary tumor.
Because hepatitis B is a leading cause of liver cancer worldwide, AFP surveillance and hepatitis B care are closely linked. See OncoFirm™’s hepatitis B panel program.
Cause 2 · Germ cell tumors
Germ cell tumors of the testis, ovary and midline
- Yolk sac tumors and embryonal carcinoma commonly produce AFP. Overall, AFP is raised in about half to two-thirds of nonseminomatous testicular cancers.
- Pure seminoma and dysgerminoma do not raise AFP. If AFP is elevated in a tumor that looks like seminoma, it is treated as containing nonseminomatous elements.
- Ovarian and extragonadal germ cell tumors, including those in the mediastinum or retroperitoneum, can also produce AFP.
- Staging and monitoring. AFP, hCG and LDH are used together for staging and follow-up. With a half-life of about five days, AFP that fails to fall as expected after surgery suggests residual disease.
Cause 3 · Pregnancy
Pregnancy and maternal serum AFP
Maternal serum AFP rises naturally during pregnancy. It has been used in second-trimester screening, typically between 15 and 20 weeks, where an unusually high result relative to the median for that week can indicate:
- Open neural tube defects such as spina bifida or anencephaly
- Abdominal wall defects such as gastroschisis or omphalocele
- Twins or more, or a pregnancy further along than estimated
- Placental problems, fetal demise or other complications
A high maternal AFP is a screening result, not a diagnosis; it leads to detailed ultrasound and counselling. AFP tumor-marker tests are not designed for prenatal screening, which uses separate, gestation-adjusted methods.
Cause 4 · Other
Other cancers and rare inherited causes
- Other tumors. Some gastric cancers (including hepatoid adenocarcinoma of the stomach) and, less often, pancreatic, biliary or lung cancers can produce AFP.
- Hereditary persistence of AFP. A rare, benign inherited trait in which AFP stays mildly to moderately raised for life without disease. Family testing can avoid unnecessary investigations.
- Ataxia-telangiectasia. Most people with this rare neurological and immune disorder have raised AFP, which tends to rise with age and is a useful diagnostic clue.
- Hereditary tyrosinemia type 1. A rare metabolic disorder of infancy associated with high AFP and a high risk of liver cancer.
Cause 5 · Measurement
Laboratory factors to rule out
- Method differences. Different immunoassays can give different numbers, so trends should be followed with the same laboratory where possible.
- Interfering antibodies. Heterophile or other interfering antibodies can rarely produce a falsely high result.
- Hook effect. At extremely high concentrations, some assays can read falsely low unless the sample is diluted.
- Wrong reference range. Infant and pregnancy results must be compared with age- or gestation-specific values.
Causes compared
Causes of high AFP at a glance
| Cause | Typical AFP pattern | What clinicians usually do next |
|---|---|---|
| Chronic hepatitis / cirrhosis | Mild, fluctuating rise | Repeat and trend; liver imaging if rising or high-risk |
| Hepatocellular carcinoma | Normal to very high; often rising | Multiphase CT or MRI; specialist review; sometimes AFP-L3 or DCP |
| Germ cell tumor | Normal to very high | Testicular or pelvic ultrasound; hCG and LDH; staging |
| Pregnancy | Raised for gestation (MoM) | Detailed ultrasound and counselling |
| Inherited (HPAF, A-T) | Stable or slowly rising | Family history, genetic evaluation |
| Lab interference | Inconsistent with the clinical picture | Repeat on another method; dilution studies |
Interpreting results
How clinicians read an AFP result
For patients and families: a single high AFP result is not a diagnosis. Many people with raised AFP do not have cancer, and some cancers do not raise AFP. Your care team will interpret the result with your history, examination and imaging.
- Context first: age, pregnancy, liver disease and symptoms change what a number means.
- Trend over time: a steadily rising AFP is more informative than one value, which is why consistent, quantitative measurement matters.
- Magnitude: very high values, especially in someone with cirrhosis and a liver lesion, raise suspicion, but diagnosis rests on imaging criteria or biopsy.
- Companion markers: AFP-L3 (a fraction of AFP more specific to liver cancer) and des-gamma-carboxy prothrombin (DCP) add information, and algorithms such as GALAD combine them with age and sex.
Liver cancer surveillance
Where AFP fits in surveillance today
The 2023 AASLD practice guidance recommends that adults at high risk of hepatocellular carcinoma, including those with cirrhosis of any cause and selected people with chronic hepatitis B, have liver ultrasound with AFP about every 6 months. AFP alone is not sensitive enough, but adding it to ultrasound improves detection of early tumors.
AFP is not recommended for screening the general population. Newer blood-based approaches are being studied: the GALAD score received FDA Breakthrough Device designation in 2020, and the related GAAD algorithm is being evaluated in U.S. real-world studies. For the bigger picture, see AI-driven biomarkers and the future of cancer screening.
OncoFirm™ research
Bringing quantitative AFP closer to the patient
Liver cancer surveillance fails most often because people do not get tested regularly. OncoFirm™’s long-term goal is a point-of-care AFP measurement that could support, not replace, guideline-based surveillance with imaging, especially where laboratory access is limited.
Quantitative, not visual
AFP is a future pipeline candidate for the same fluorescent strip and handheld reader as OncoFirm™’s lead CEA and PSA programs, designed to report numbers rather than lines. Platform AFP program
Built for trends
Surveillance means repeated testing every few months, so a reproducible, calibrated value that can be compared over time matters more than a single cutoff.
Linked to hepatitis B care
People living with chronic hepatitis B are a key surveillance group, connecting AFP with OncoFirm™’s hepatitis B program.
Panels and algorithms
Research on combining AFP with other markers and validated algorithms, in the spirit of GALAD-type scores. AI-assisted diagnostics
Explore the Cancer Biomarker Atlas 2026 and one reader, one strip design.
OncoFirm™ AFP is a future pipeline concept. It is in development, has not been cleared or approved by the FDA or any other regulatory authority, and is not available for sale.
FAQ
Frequently asked questions
What is a normal AFP level?
In non-pregnant adults AFP is usually below about 8 to 10 ng/mL; Mayo Clinic Laboratories, for example, reports an adult reference of under 8.4 ng/mL. Ranges differ between laboratories and are much higher in newborns and during pregnancy.
What causes high AFP besides cancer?
Common non-cancer causes include chronic hepatitis B or C, cirrhosis, liver regeneration after injury, and pregnancy. Rarer causes include hereditary persistence of AFP and ataxia-telangiectasia. Newborns and young infants also have naturally high AFP.
Does a high AFP mean liver cancer?
Not necessarily. Mild elevations are common in chronic liver disease, and about 30% of liver cancers do not raise AFP at all. A raised AFP prompts further evaluation, usually liver imaging, and diagnosis depends on imaging or biopsy rather than AFP alone.
What AFP level is concerning?
There is no single cutoff that diagnoses cancer. Very high or steadily rising values, especially in someone with cirrhosis or chronic hepatitis B, are more concerning than a single mildly raised result. Clinicians look at the trend, use the same laboratory where possible and confirm with imaging.
Can AFP be used to screen for cancer?
AFP is not recommended for screening the general population. For people at high risk of liver cancer, such as adults with cirrhosis, AASLD guidance recommends ultrasound with AFP about every 6 months.
Does OncoFirm™ offer an AFP test?
Not yet. Quantitative AFP is a future pipeline candidate for OncoFirm™'s fluorescent lateral flow platform. It is in development, has not been cleared or approved by the FDA or any other regulatory authority, and is not available for sale.
Keep reading
Related guides
Sources
References
- Singal AG, Llovet JM, Yarchoan M, et al. AASLD Practice Guidance on prevention, diagnosis, and treatment of hepatocellular carcinoma. Hepatology. 2023;78(6):1922–1965. journals.lww.com/hep/fulltext/2023/12000/aasld_practice_guidance_on_prevention,_diagnosis,.27.aspx
- Mayo Clinic Laboratories. Alpha-fetoprotein (AFP) tumor marker, serum: test overview. www.mayocliniclabs.com/test-catalog/overview/8162
- Mayo Clinic Laboratories. Alpha-fetoprotein (AFP), single marker screen, maternal, serum: test overview. www.mayocliniclabs.com/test-catalog/overview/113382
- American College of Medical Genetics and Genomics. Laboratory screening and diagnosis of open neural tube defects, 2019 revision: a technical standard. Genetics in Medicine. 2019. www.sciencedirect.com/science/article/pii/S109836002101248X
- University of Washington. Hepatitis C Online: Surveillance for hepatocellular carcinoma (core concept). www.hepatitisc.uw.edu/pdf/evaluation-staging-monitoring/surveillance-hepatocellular-carcinoma/core-concept/all
- Roche. FDA grants Breakthrough Device Designation for Roche's Elecsys GALAD score to support earlier diagnosis of hepatocellular carcinoma. March 4, 2020. www.roche.com/investors/updates/inv-update-2020-03-04
- Johns Hopkins Medicine. Testicular cancer tumor markers. www.hopkinsmedicine.org/health/conditions-and-diseases/testicular-cancer/testicular-cancer-tumor-markers
- Stray-Pedersen A, Borresen-Dale AL, Paus E, et al. Alpha fetoprotein is increasing with age in ataxia-telangiectasia. European Journal of Paediatric Neurology. 2007;11(6):375–380. www.sciencedirect.com/science/article/abs/pii/S1090379807000773
About this article. Written by the OncoFirm™ Scientific Team from clinical guidelines, laboratory references and peer-reviewed publications, all linked above. This article is for education and is not medical advice; it cannot be used to interpret an individual test result. OncoFirm™ assays are in development, have not been cleared or approved by the FDA and are not available for sale.
Collaborate on liver cancer surveillance research
Hepatology, oncology and global-health partners interested in point-of-care AFP measurement and hepatitis B care can explore joint studies with OncoFirm™. Collaboration inquiry