Alpha-fetoprotein in plasma and serum of healthy adults: preanalytical, analytical and biological sources of variation and construction of age-dependent reference intervals

• Published in: Scandinavian journal of clinical and laboratory investigation Vol. 61; no. 3; pp. 205 - 215
• Main Authors: CHRISTIANSEN, M, HØGDALL, C. K, ANDERSEN, J. R, NØRGAARD-PEDERSEN, B
• Format: Journal Article
• Language: English
• Published: Oslo Informa UK Ltd 2001; Taylor & Francis; Scandinavian University Press
• Subjects: Adult; Age Distribution; alpha-Fetoproteins - analysis; alpha-Fetoproteins - immunology; Antibodies, Monoclonal; Biological and medical sciences; Biomarkers, Tumor - analysis; Biomarkers, Tumor - blood; Chemistry, Clinical - methods; Chemistry, Clinical - standards; Enzyme-Linked Immunosorbent Assay - standards; Epitopes - analysis; Epitopes - immunology; Female; Host-tumor relations. Immunology. Biological markers; Humans; Male; Medical sciences; Middle Aged; Reference Values; Sex Distribution; Tumors; Words Age Dependence Alpha-FETOPROTEIN Blood Donors Malignancy Monoclonal Antibodies Sex Variation Tumor Marker; Human; Reference value; Biochemical analysis; Antigenic determinant; Healthy subject; Antibody; Variations; Tumoral marker; α-Fetoprotein; Immunological method; Blood plasma; Specificity; Pre analytical step; Clinical biology; Distribution; Adult; Serum; Age; Quantitative analysis
• ISSN: 0036-5513; 1502-7686
• DOI: 10.1080/003655101300133649

Alpha-fetoprotein (AFP) is a tumor marker for hepatomas and germ cell tumors, and the serum concentration has prognostic significance in other diseases. We examined the normal serum concentration of AFP in adults and sources of variation in the immunochemical variation of AFP. The serum concentration of the tumor marker alpha-fetoprotein (S-AFP) was log-normally distributed in 284 adult blood donors. S-AFP increased with age (p<10 7), whereas no gender-related difference was found. Reference intervals (95-interpercentile) were constructed for persons 40 years (0.60-9.30kIU/L) and >40 years (1.40-12.60kIU/L). The concentration of AFP was significantly, albeit slightly, higher in serum than in plasma, whereas hemolysis, pretreatment with KCl and food intake did not influence S-AFP. S-AFP only changed 6% when measured twice 2 months apart (p=0.04). Three enzyme immunoassays, using three different anti-AFP monoclonal antibodies for detection, were compared and two assays gave S-AFP values significantly higher, 2.8% (p=0.03) and 19.0% (p<10 4), than the other assay. Thus, the choice of antibody may influence the result of immunochemical concentration determination. This can b eexplained by the existence of conformational variants of AFP with different antibody reactivities, and calls for careful standardization of monoclonal antibodies used in assays for AFP. With broad population reference ranges and slight intra-personal variation, the most effective reference range for S-AFP is previous values obtained in the same person.