Usually, you have a very small amount of alpha-fetoprotein (AFP) in your body. But when you have liver disease, some types of cancer, or are pregnant, you'll usually have more of it in your blood. An AFP tumor marker test checks the level of this protein.
A higher AFP level doesn't always mean you have a health problem. Some people simply have more AFP than is typical.
Why You Get Tested
Your doctor may want you to have an AFP tumor marker blood test to:
- Narrow down the cause of a lump in your liver, testicles, or ovaries
- Help decide the best treatment for cancer
- See how well a cancer treatment is working
- Make sure cancer hasn't come back after treatment
AFP tests can also check for birth defects in an unborn baby. Doctors may test spinal fluid for AFP, too, depending on what they're looking for.
How It's Done
You can have an AFP blood test at your doctor's office or in a hospital. A technician will use a needle to take a sample from a vein in your hand or arm. You may feel a small prick and have a little bleeding or bruising where the needle goes in.
Then they'll send your blood to a lab.
What the Results Mean
Doctors measure AFP in your blood in nanograms per milliliter (ng/mL). The normal level for most healthy adults is between 0 and 8 ng/mL. The reference range will vary with pregnant women.
Many things, including cancer, liver diseases like hepatitis and cirrhosis, as well as an injured liver that's healing, can raise that number. You'll likely need more tests to get the right diagnosis.
Very high levels -- 500 to 1,000 ng/mL or more -- are often a sign of certain kinds of cancer. Other types of cancer may not show up on an AFP test.
When you have liver disease already, an AFP of more than 200 ng/mL usually means you have liver cancer.
AFP-L3% Test
For people who have a raised AFP but less than 200 ng/mL, the doctor may want to do an AFP-L3% test (also called L3AFP). This compares the amount of a specific kind of AFP (AFP-L3) to the total amount of AFP in your blood. It helps doctors figure out what's going on, especially when you have a chronic liver disease, like cirrhosis.
An AFP-L3% result of 10% or more suggests that you have higher odds of getting liver cancer and your doctor should watch carefully for signs of it.
After Diagnosis
These tests can also help your doctor check how well your cancer treatment is working. Ideally, you want to get back to a normal level.
Regular AFP tests can help catch a relapse early, too. If the cancer you had before comes back, your AFP level will go up, sometimes before you have any symptoms.