- Last Update On : 2013-02-17
Alpha fetoprotein (AFP) is a 69,000 kD single chain polypeptide which is similar in size and structure to human serum albumin. In human embryos, AFP is first made in the yolk sac and later in the fetal liver. As the fetal liver matures, it gradually switches to albumin synthesis. In the fetus, AFP synthesis gradually declines to the normal adult range by 6 to 12 months after birth. During pregnancy, AFP levels in maternal serum rise steadily to a peak of approximately 500 ng/mL at about 32 weeks of gestation. Thereafter, they decline until term.
As a tumor marker, AFP is useful in detecting germ cell tumors of the ovary and testis, primary hepatocellular carcinoma in adults, and hepatoblastoma in children. AFP is not specific for these cancers. In addition to the elevations seen during pregnancy, serum values can be high in patients with a variety of liver diseases. Modest elevations of AFP occur in about 20% of patients with hepatitis, cirrhosis, biliary tract obstruction,