|Biochemistry >> Oncology
AFP is a single chain glycoprotein of 591 amino acids that is structurally related to albumin. Synthesis of AFP occurs primarily in the liver and yolk sac of the fetus. It is secreted into fetal serum, reaching a peak at about 13 weeks gestation and gradually declining thereafter. After birth, circulating concentrations decrease with a half-life of 5 days to adult levels by 8-10 months of age. The higher values in early childhood must be considered when using AFP measurement in testicular yolk sac tumour, the commonest testicular neoplasm in infants. Elevated circulating levels of AFP are observed in several malignant diseases, most commonly in hepatocellular carcinoma (HCC) and germ cell tumours where measurement is an important part of management. AFP is also used in the diagnosis of hepatoblastoma. Elevated serum AFP occurs in pregnancy and transient increases in serum AFP may occur in liver regeneration, hepatitis, chronic liver disease and cirrhosis (especially in hepatitis), biliary tract obstruction, alcoholic liver disease, ataxia telangiectasia and hereditary tyrosinaemia.
Testicular and other germ cell tumours (GCT)
Diagnosis: serum AFP (and hCG) marker measurement are an essential part of the clinical workup of GCT.
Diagnosis: measurement of AFP and abdominal ultrasound is used in patients at high risk of HCC, eg. liver cirrhosis related to hepatitis B/C. A rising AFP should be investigated even if initial imaging is negative.
Adult serum (non-pregnant): <14 µg/L
Non-infant CSF (>2 months of age): <3 µg/L
|Sample & container required
|SST (gold top) preferred, serum (red top) accepted
|For CSF analysis: 0.5 mL
|For CSF analysis: Universal container
CSF analysis: Samples should be as fresh as possible. Avoid repeated freeze/thaw cycles.