ALPHA - Foetoprotein (AFP) (Tumour Marker)

Immunology

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Description

The main application of all tumour markers is monitoring for relapse or progression. Use as a diagnostic aid requires care and knowledge of the test limitations. Opportunistic screening is discouraged. Alpha-fetoprotein ( AFP ) is a single-chain glycoprotein with a molecular mass of approximately 67,500 daltons. AFP shares considerable sequence homology with albumin, and is produced by the foetus primarily in cells of the yolk sac, gastrointestinal tract and liver. AFP appears as a major serum protein in the foetus, but its concentration decreases rapidly toward birth. The reappearance of elevated AFP concentrations in adult serum has been observed not only during pregnancy, but also in conjunction with several benign and malignant diseases [4]. Guidelines for the use of tumour markers suggest that AFP, along with human chorionic gonadotropin ( hCG ) should be used for the screening, diagnosis, staging and monitoring of germ cell tumours. They also state that AFP can be used for the differential diagnosis of non-seminoma carcinoma [1,3]. Serial measurements of serum AFP, hCG and LDH have been shown to reflect the effectiveness of therapeutic regimens in patients with non-seminomatous testicular tumours and aid in predicting prognosis [2]. Raised AFP can be seen in other malignancies such as hepatocellular carcinoma, gastrointestinal cancer and pulmonary cancer. Serum AFP is frequently elevated in benign hepatic conditions such as acute viral hepatitis, chronic active hepatitis and cirrhosis. AFP allotyping can be performed to determine if the AFP is of yolk sac or liver origin [2].

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Indications

Germ cell tumours ( non-seminoma carcinoma ). Monitoring and diagnosis of Hepatocellular carcinoma, hepatoblastoma.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ), 2mL Heparin ( Lithium or Sodium ) or EDTA Plasma. Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Serum or plasma reference range:Age related. Contact laboratory for interpretation.Age | Range Birth | 50000 - 150000 kU/L2 weeks | 7000 - 20000 kU/L 4 weeks | 1500 - 2500 kU/L6 weeks | 200 - 400 kU/L 8 weeks | 50 - 100 kU/L10 weeks | 6 - 12 kU/L 3 months - 50 years | 3 - 8 kU/L50 - 70 years | < 15 kU/L70 - 90 years | < 20 kU/LHigher concentrations are seen in the premature infant and the degree of prematurity will influence the age ( from birth ) at which basal levels are attained.Reference range established by manufacturer and verified in house.

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Turnaround Time

Within 2 days

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Testing Frequency

Daily

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References

Sturgeon CM and Diamandis EP. Use of tumour markers in clinical practice: Quality requirements. The National Acadamy of Clinical Biochemistry. Laboratory medicine practice guidelines. 2009. [Ref 1]Sturgeon CM et al. Serum Tumour Markers:How to order and interpret them. British Medical Journal. 2009. 339; 852-858.PRU Handbook of Clinical Immunochemistry. 9th Edition. 2007. [Ref 2]. Sturgeon C. Practice guidelines for tumour marker use in the clinic. Clin Chem. 2002. 48( 8 ):1151-1159. [Ref 3]Gerald J, and Mizejewski. Alpha-fetoprotein Structure and Function: Relevance to Isoforms, Epitopes, and Conformational Variants. Experimental Biology and Medicine. 2001. 226:377-408. [Ref 4]Duffy M.J. Tumour Markers in Clinical Practice: A review focusing on common solid cancers. Med Princ Pract. 2013. 22: 4-11. [Ref 5].

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