Alpha-fetoprotein (AFP) is a protein normally made by the liver and yolk sac of a developing baby. AFP levels go down soon after birth. It is not normally found in healthy adults.
Why an AFP test is done
Your doctor may order an AFP test to help diagnose, monitor response to treatment and check for recurrence of the following cancers:
- a type of testicular cancer called non-seminoma germ cell tumour
- a type of ovarian cancer called germ cell tumour
In rare cases an AFP test may be used to help diagnose the following cancers:
- bile duct
Doctors may order an AFP test when a woman is pregnant to look for birth defects and genetic disorders, such as Down syndrome, in developing babies.
In the past, doctors used the AFP test to help them diagnose a type of liver cancer called hepatocellular carcinoma. But the AFP test can’t specifically identify hepatocellular carcinoma, so doctors no longer use it to diagnose liver cancer. Doctors may still order an AFP test to help diagnose some liver problems such as cirrhosis and hepatitis.
How an AFP test is done
An AFP test is usually done in a private or hospital lab. It is measured with a blood test. No special preparation is needed. The blood sample is analyzed by special machines.
What the results mean
AFP may be found in the blood if you have one of the following non-cancerous conditions:
- a rare inherited disorder called ataxia-telangiectasiaataxia-telangiectasiaA rare genetic disease that affects the nervous system, immune system and other body systems. Signs and symptoms include loss of balance, poor coordination, frequent infections, red eyes (due to widening of blood vessels) and abnormal eye movements.
It may also suggest that a person may have a testicular or ovarian germ cell tumour.
If someone with cancer had a high AFP level before treatment, lower AFP levels may mean that the cancer has responded well to treatment. Higher AFP levels may mean that the cancer is not responding well to treatment, is still growing or has come back (recurred). A slight increase may not be significant. The doctor looks at trends in the increase over time.
What happens if a change or abnormality is found
The doctor will decide if more tests, procedures, follow-up care or additional treatment is needed.
Special considerations for children
The preparation for an AFP depends on the age and experience of the child. Find out more age-specific information on how to prepare a child for tests and procedures.