AFP is usually produced by the yolk sac and the liver during fetal development.2 AFP is the most prevalent protein found in the blood of the human fetus and is believed to play a role similar to serum albumin, which is to transport protein of hormones and micronutrients. Typically, AFP decreases steadily during the first year of life. In response to fetal development, AFP levels will rise in mothers' blood, urine, and amniotic fluid during pregnancy. Very high levels of AFP during pregnancy are associated with fetal malformations.2
As a tumor marker, AFP analysis is used in the post-treatment phase of previously diagnosed cancers and in early surveillance of cancer survivors, where the rate of decrease of AFP has diagnostic and prognostic value. Malignant conditions associated with elevated levels of AFP in the blood include:
- Hepatocellular carcinoma (a liver biopsy of a hepatocellular carcinoma is shown in the image)
- Germ cell and yolk sac tumors
- Metastatic carcinomas of the liver
