Alpha-Fetoprotein (AFP): What the Blood Test Measures and What Your Levels Mean
Alpha-fetoprotein (AFP) is a protein made mainly by the liver and yolk sac of a developing foetus. Levels fall sharply after birth, so healthy adults usually have very little, typically less than 10 kU/L [1]. An AFP blood test measures this protein and is used mainly to investigate liver conditions and certain germ cell tumours [2].
What is alpha-fetoprotein (AFP)?
AFP is a protein that plays a vital role in foetal development. During pregnancy, AFP levels are naturally high. However, shortly after birth, these levels drop significantly.
In adults, AFP is usually present only in very low amounts. When levels rise above this normal baseline, it can be an indication that the liver is regenerating cells or that there is an underlying health issue.
AFP stands for alpha-fetoprotein, sometimes written alphafetoprotein. On a blood test request form it may simply appear as "AFP".
What is an AFP blood test used for?
An AFP blood test is used mainly to investigate liver health and to help detect and monitor certain tumours. It is a straightforward blood sample; the result is interpreted alongside other tests rather than on its own.
- Liver surveillance: monitoring adults with cirrhosis or chronic liver disease, usually alongside an ultrasound scan [3].
- Chronic liver conditions: tracking AFP over time in people with hepatitis or cirrhosis [2].
- Germ cell tumours: AFP is used as a tumour marker for certain germ cell tumours, such as non-seminomatous testicular cancer, both to aid diagnosis and to monitor treatment [1][2].
What is the normal range for AFP?
In healthy adults, AFP is usually present only in very low amounts, typically less than 10 kU/L [1]. When a blood test reveals levels above this range, it prompts a closer look.
Your report shows the reference range used by the laboratory next to your result. A doctor can help interpret your result in the context of your health.
What do high AFP levels mean?
An elevated AFP level does not automatically mean a diagnosis of cancer. AFP levels can be raised for several non-cancerous reasons, including liver inflammation (hepatitis), cirrhosis, and even during pregnancy [5].
| Possible reason for raised AFP | What the sources say |
|---|---|
| Liver repair | AFP is produced by regenerating liver cells, so a raised result may reflect the liver repairing damage from a viral infection, alcohol use or other causes [4]. |
| Hepatitis or cirrhosis | Slightly raised AFP levels are common in chronic hepatitis or cirrhosis and do not necessarily indicate cancer [2]. |
| Pregnancy | AFP levels are naturally high during pregnancy [5]. |
| Liver cancer (HCC) | AFP is used, with imaging, in surveillance for hepatocellular carcinoma in people at higher risk [3][4]. |
| Germ cell tumours | Raised AFP can be linked to certain germ cell tumours, such as those affecting the testicles or ovaries [2]. |
Conversely, some people with early-stage liver cancer may have normal AFP levels. Because of this variability, an AFP test is rarely used in isolation.
AFP and liver cancer surveillance
For individuals with cirrhosis or chronic liver disease, the risk of developing hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is increased. The National Institute for Health and Care Excellence (NICE) recommends that adults with cirrhosis are offered surveillance for HCC every six months [3].
This surveillance typically involves an ultrasound scan, often accompanied by an AFP blood test. While AFP is not a perfect marker on its own, when used alongside imaging, it helps healthcare professionals monitor changes and detect potential issues at an earlier, more treatable stage [4].
How are AFP results interpreted?
If your results show higher-than-normal levels, your doctor will consider them alongside your medical history, symptoms, and the results of other investigations, such as liver function tests and ultrasound or MRI scans.
Tracking AFP over time can add to a single result. In people with hepatitis or cirrhosis, healthcare professionals can use changes in AFP to gauge liver inflammation and monitor treatment; a steady decrease often indicates that the liver is responding to therapy.
For germ cell tumours, a decrease in AFP levels following therapy suggests the treatment is working, while a subsequent rise may suggest a recurrence [2].
Who might consider an AFP test?
Many liver conditions, including cirrhosis and early-stage liver cancer, often develop without causing noticeable symptoms. By the time symptoms such as jaundice, fatigue, or abdominal pain appear, the disease may have already reached an advanced stage.
- People with chronic hepatitis B or C.
- People with a history of heavy alcohol use.
- People diagnosed with cirrhosis or another chronic liver condition, including those following a recommended surveillance programme.
- People with a family history of liver disease who want to discuss their results with a healthcare professional.
An AFP test does not replace an assessment by your doctor. The results may support informed conversations with a healthcare professional about the next appropriate step.
Frequently asked questions
What does AFP stand for in a blood test?
AFP stands for alpha-fetoprotein, a protein made by the liver and yolk sac of a developing foetus. In adults it is usually present only in very low amounts [1].
What is the normal range for an AFP blood test?
In healthy adults AFP is typically less than 10 kU/L [1]. Your report shows the laboratory's reference range next to your result.
Is an AFP blood test used for liver cancer?
Yes, as part of surveillance. NICE recommends that adults with cirrhosis are offered surveillance for HCC every six months, typically an ultrasound scan often accompanied by an AFP test [3]. A raised AFP alone does not mean cancer, and some people with early-stage liver cancer have normal AFP levels.
Is AFP a liver test?
AFP is closely linked to the liver: raised levels can reflect liver regeneration, hepatitis or cirrhosis [2][4]. It is usually read alongside liver function tests and imaging rather than on its own.
References
South Tees Hospitals NHS Foundation Trust. (n.d.). Alpha Fetoprotein (AFP). https://www.southtees.nhs.uk/services/pathology/tests/alpha-fetoprotein-afp/
Lab Tests Online UK. (n.d.). AFP Tumour Marker Test. https://labtestsonline.org.uk/tests/afp-tumour-marker-test
National Institute for Health and Care Excellence (NICE). (2017). Surveillance for hepatocellular carcinoma. https://www.nice.org.uk/guidance/qs152/chapter/quality-statement-4-surveillance-for-hepatocellular-carcinoma
British Liver Trust. (n.d.). Regular checks for liver cancer (surveillance). https://britishlivertrust.org.uk/information-and-support/diagnosis-and-care/regular-checks-for-liver-cancer/
Macmillan Cancer Support. (n.d.). Blood tests. https://www.macmillan.org.uk/cancer-information-and-support/diagnostic-tests/blood-tests
