Alpha – Fetoprotein (Blood)

Diagnostic Use

Plasma/serum alpha-fetoprotein (AFP) has been used to aid the diagnosis and monitoring of hepatocellular carcinoma(HCC). AFP alone overall has limited sensitivity and specificity in detecting HCC and its diagnostic performance varies depending on e.g. cohort, cut point used, size of tumour and degree of tumour cell differentiation. Some hepatocellular carcinoma can have no AFP elevation thus a normal level does NOT exclude the condition. Its diagnostic value can be enhanced by combining its interpretation with radiological investigations, other novel biomarkers or molecular markers.

AFP can be mildly raised in chronic active hepatitis or cirrhosis without hepatic neoplasm, typically remain below100ug/L while cut point at 400-500ug/L has been described to distinguish malignant from non-malignant chronic hepatic conditions. Acute hepatitis can see AFP level rise into the 10-1000ug/L range. It generally peaks when liver destruction issubsiding and remodelling/regeneration begins. ​

AFP can also be used to aid diagnosis and monitoring of some non-seminomatous testicular or ovarian tumours like yolk sac (endodermal sinus) tumour or immature teratoma. 

As AFP is raised in pregnancy after 12 weeks gestation, it is used as a component in the 2nd trimester serum maternal screen for e.g. neural tube defect. (Note : the AFP test offered at CMH laboratory is NOT designed for this risk calculation – refer to NZ’s Antenatal Screening Programme)​

A rare cause for persistently raised AFP is Familial or Hereditary Persistence of AFP. This is a benign autosomal dominant condition with raised AFP found in some first degree family members.​

The half-life of AFP in vivo is about 5 days in adults.  In neonates, AFP declines with a half-life of 6 days until 28 days of age; after this the rate of decline is slower – see table under “Reference Intervals”.

Reference Intervals

2 years to Adult (non-pregnant): 0 – 10ug/L

For detailed breakdown of reference intervals for AFP in children between 0 days to 2 years (term vs pre-term) : see LabPLUS testguide on AFP