Alpha-fetoprotein

Alpha-fetoprotein - A protein that is produced in the liver and gastrointestinal tract of the fetus and by some abnormal tissues in adults. Alpha-fetoprotein (AFP) can be measured in the maternal blood from the latter part of the 1st trimester of pregnancy, and its concentration rises between the 15th and 20th weeks.

Raised levels of AFP are associated with fetal neural tube defects, such as spina bifida or anencephaly, and certain kidney abnormalities. High levels of AFP also occur in multiple pregnancies (see pregnancy, multiple) and threatened or actual miscarriage. AFP levels may be unusually low if the fetus has Down’s
syndrome.

For this reason, measurement of blood AFP is included in blood tests, which are used to screen pregnant women for an increased risk of Down’s syndrome. AFP levels are commonly raised in adults with hepatoma (see liver cancer), cancerous teratoma of the testes or ovaries, or cancer of the pancreas, stomach, or lung. For this reason, AFP is known as a tumour marker.

AFP levels can be used to monitor the results of treatment of certain cancers; increasing levels after surgery or chemotherapy may indicate tumour recurrence. However, AFP levels are also raised in some noncancerous conditions, including viral and alcoholic hepatitis and cirrhosis.