Alpha-fetoprotein (AFP) test

The AFP test measures how much alpha-fetoprotein is in your blood. It is used to screen for certain cancers and monitor response to treatment. It is also part of the second trimester pregnancy screening tests.

On this page, you can find the following information:

What is alpha-fetoprotein (AFP)?

Alpha-fetoprotein (AFP) is a protein that is normally produced by the developing foetus (baby) but is also present in small amounts in normal adults. It can be produced by certain tumours including some types of liver cancer (hepatocellular carcinoma) or testicular cancer (cancer of the testis).

Why is an alpha-fetoprotein (AFP) test done?

AFP is used to detect certain cancers especially of the liver and testis and less commonly other cancers (eg, stomach, bowel, lung, breastlymphoma). It is also used to monitor response to treatment, in people with these cancers.

During pregnancy, the AFP test is part of the second trimester screening tests used to screen for conditions such as spinal bifida and Down syndrome, to heck for multiple pregnancies and get an accurate due date. This is usually done between weeks 14–18 of pregnancy, mainly in women who have not had the first trimester screening tests. Read more about pregnancy screening tests and checks.
 

How do I prepare for an AFP test?

Generally, you won't need to do anything before having this test. It can be done at any time of the day. It is a simple blood test where a small amount of blood is taken by placing a needle placed in a vein in your arm. Read more about blood tests.

What do the results of an AFP test mean?

Cancers

Increased AFP levels can be caused by liver cancer, cancer of the testis or less commonly other cancers (for example, stomach, bowel, lung, breast, lymphoma). Slightly increased levels of AFP are common in people who have chronic hepatitis or cirrhosis and do not necessarily indicate the presence of cancer. 

In general, AFP decreases when your body responds to anti-cancer therapy. If AFP does not return to normal by about 1 month after cancer therapy, some of the tumour may still be present.

Pregnancy

A higher AFP test result suggests that you are at greater risk of having a baby with a condition. However, most of the time the baby won't have the condition, the result just shows that the risk is greater than it is for other women who have been screened. 

The interpretation of the screening test result should be provided by your midwife, a genetic counsellor or doctor. They will be able to explain the meaning of the result and discuss the available options. If the result appears to be in the ‘higher risk’ category, further tests are needed to confirm a diagnosis. For possible chromosome abnormalities, an amniocentesis or chorionic villus sample will usually be needed. Other disorders may be detected using a detailed ultrasound scan.

Learn more

The following is further reading that gives you more information on the alpha-fetoprotein (AFP) test. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Antenatal screening for down syndrome and other conditions National Screening Unit, NZ, 2014
Alpha-fetoprotein (AFP) Australasian Association of Clinical Biochemists
Maternal screening Australasian Association of Clinical Biochemists

Information for healthcare providers

Appropriate use of tumour markers BPAC, NZ, 2010
Alpha-fetoprotein (AFP) tumor marker LabTests Online, 2019

Credits: Health Navigator Editorial Team.