Alpha-fetoprotein (AFP) is a protein that is produced mainly by the fetal liver and yolk sac during pregnancy. After birth, AFP levels normally decrease and remain very low in healthy adults.

What the AFP test is used for

In adults, an AFP blood test is used to:

• Help diagnose and monitor liver cancer (especially hepatocellular carcinoma).

• Evaluate and monitor certain germ cell tumors, such as some cancers of the testicles and ovaries.

• Monitor treatment effectiveness and check for cancer recurrence after treatment.

• Help evaluate chronic liver diseases, such as hepatitis or cirrhosis, in people at increased risk for liver cancer.

During pregnancy, AFP is used as part of prenatal screening to help assess the risk of certain fetal conditions, although it is interpreted together with other tests.

What high AFP levels may mean

Elevated AFP levels can occur with:

• hepatocellular carcinoma

• Certain testicular or ovarian germ cell tumors

• Chronic liver diseases, such as hepatitis or cirrhosis

• Pregnancy (normally elevated)

What low AFP levels mean

In non-pregnant adults, low or undetectable AFP levels are generally considered normal.