Alpha-fetoprotein
Alpha-fetoprotein (AFP) is an important plasma protein synthesized by the yolk sac and fetal liver. In adults, its main utility is as a tumor marker, primarily for hepatocellular carcinoma or teratoma. Functionally it is the fetal homologue of albumin i.e. it acts as a major carrier protein in the antenatal circulation. It is encoded by the AFP gene .
Alpha-fetoprotein (AFP) elevation
This may occur in a broad spectrum of conditions:
- liver tumors (hepatocellular carcinoma, hepatoblastoma)
- <10 ng/mL is within normal limits
- >20 ng/mL is above normal limits but has low specificity for tumor since it may occur in a setting of diffuse liver injury
- increasing AFP over time, especially with stable AST and ALT is suspicious
- AFP has a low sensitivity and specificity for hepatic malignancy
- in the presence of an HCC, an elevated AFP level is indicative of an aggressive tumor
- pancreatic tumors
- antenatal conditions (maternal serum AFP (MSAFP))
- normal pregnancy
- rises from 12 weeks and peaks during the early 3trimester
- increased in multifetal pregnancy
- neural tube defects
- omphalocele
- OEIS complex
- cloacal exstrophy
- gastroschisis
- limb-body wall complex
- placental chorioangioma
- placental lakes
- normal pregnancy
- germ cell tumors
- sacrococcygeal teratoma
- intracranial embryonal carcinoma
- ovarian embryonal carcinoma
- immature teratoma
- epignathus
- yolk sac tumors
- testicular yolk sac tumor
- ovarian yolk sac tumor
- intracranial yolk sac tumor
- ovarian Sertoli-Leydig cell tumor (rarely)
- other tumors
- non-malignant conditions
- biliary atresia
- chronic active hepatitis
- cirrhosis
- hereditary tyrosinemia type I
- hereditary persistence of AFP
Alpha-fetoprotein (AFP) reduction
This may be seen in pregnancy.
AFP reduction may be associated with:
- certain chromosomal anomalies
- Cornelia de-Lange syndrome
See also
Siehe auch:
