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1
Department of Clinical Biochemistry AKH and Skejby Hospital, Aarhus University Hospital, DK-8000 Aarhus C, Denmark.
2
Department of Pharmacology, University of Bergen, 5021
Bergen, Norway.
3
Axis Biochemicals, 0510 Oslo, Norway.
4
Department of Biochemistry, Trinity College, University
of Dublin, Dublin 2, Ireland.
5
Department of Pharmacology, University of Oxford, Oxford
OX1 3QT, United Kingdom.
6
Department of Pediatric Research, University of Oslo,
0316 Oslo 3, Norway.
a Address correspondence to this author at: Department of Clinical Biochemistry, AKH, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark. Fax 45-8949-3060; e-mail ene{at}post9.tele.dk
Background: There is a need for systematic evaluation of methods before their release to the market. We addressed this problem in novel homocysteine assays as part of an European Demonstration Project involving six centers in four countries.
Methods: Two immunological methods for measurement of plasma total homocysteine (P-tHcy), the fluorescence polarization immunoassay (FPIA) and the enzyme immunoassay (EIA), were compared with two comparison methods, HPLC and gas chromatography–mass spectrometry (GC-MS). All laboratories performed the following procedures: (a) familiarization; (b) determination of linearity and precision by analyzing five plasma samples with interrelated concentrations for 20 days; (c) correlation using patients’ samples; and (d) assessment of long-term performance.
Results: Both immunological methods were linear for P-tHcy between 5 and 45 µmol/L. The intralaboratory imprecision (CV) was <5% for FPIA and <9% for EIA used with a sample processor. The bias was -2% to 3% for FPIA and 2–4% for EIA used with a sample processor.
Conclusions: The immunological methods provide results with little bias compared with HPLC and GC-MS. The imprecision of the assays must be considered in the context of their intended use(s).
The following articles in journals at HighWire Press have cited this article:
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  A. D. Dangour, E. Breeze, R. Clarke, P. S. Shetty, R. Uauy, and A. E. Fletcher Plasma Homocysteine, but Not Folate or Vitamin B-12, Predicts Mortality in Older People in the United Kingdom J. Nutr., June 1, 2008; 138(6): 1121 - 1128. [Abstract] [Full Text] [PDF]
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 E. N. Rowan, H. O. Dickinson, S. Stephens, C. Ballard, R. Kalaria, and R. Anne Kenny Homocysteine and post-stroke cognitive decline Age Ageing, May 1, 2007; 36(3): 339 - 343. [Full Text] [PDF]
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 A. L. Morkbak, A.-M. Hvas, Z. Lloyd-Wright, T. A.B. Sanders, O. Bleie, H. Refsum, O. K. Nygaard, and E. Nexo Effect of Vitamin B12 Treatment on Haptocorrin Clin. Chem., June 1, 2006; 52(6): 1104 - 1111. [Abstract] [Full Text] [PDF]
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 A. M Devlin, R. Clarke, J. Birks, J. G. Evans, and C. H Halsted Interactions among polymorphisms in folate-metabolizing genes and serum total homocysteine concentrations in a healthy elderly population Am. J. Clinical Nutrition, March 1, 2006; 83(3): 708 - 713. [Abstract] [Full Text] [PDF]
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H. Refsum, C. Johnston, A. B. Guttormsen, and E. Nexo Holotranscobalamin and Total Transcobalamin in Human Plasma: Determination, Determinants, and Reference Values in Healthy Adults Clin. Chem., January 1, 2006; 52(1): 129 - 137. [Abstract] [Full Text] [PDF]
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A. Windelberg, O. Arseth, G. Kvalheim, and P. M. Ueland Automated Assay for the Determination of Methylmalonic Acid, Total Homocysteine, and Related Amino Acids in Human Serum or Plasma by Means of Methylchloroformate Derivatization and Gas Chromatography-Mass Spectrometry Clin. Chem., November 1, 2005; 51(11): 2103 - 2109. [Abstract] [Full Text] [PDF]
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 E.-C. Chan, P.-Y. Chang, T.-L. Wu, and J. T. Wu Enzymatic Assay of Homocysteine on Microtiter Plates or a TECAN Analyzer Using Crude Lysate Containing Recombinant Methionine {gamma}-Lyase Ann. Clin. Lab. Sci., April 1, 2005; 35(2): 155 - 160. [Abstract] [Full Text] [PDF]
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H. Refsum, A. W. Grindflek, P. M. Ueland, A. Fredriksen, K. Meyer, A. Ulvik, A. B. Guttormsen, O. E. Iversen, J. Schneede, and B. F. Kase Screening for Serum Total Homocysteine in Newborn Children Clin. Chem., October 1, 2004; 50(10): 1769 - 1784. [Abstract] [Full Text] [PDF]
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 L. A.D.M. van Osch, E. Hogervorst, M. Combrinck, and A. D. Smith Low thyroid-stimulating hormone as an independent risk factor for Alzheimer disease Neurology, June 8, 2004; 62(11): 1967 - 1971. [Abstract] [Full Text] [PDF]
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T. Arndt, B. Guessregen, A. Hohl, and B. Heicke Total Plasma Homocysteine Measured by Liquid Chromatography-Tandem Mass Spectrometry with Use of 96-Well Plates Clin. Chem., April 1, 2004; 50(4): 755 - 757. [Full Text] [PDF]
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H. Refsum, A. D. Smith, P. M. Ueland, E. Nexo, R. Clarke, J. McPartlin, C. Johnston, F. Engbaek, J. Schneede, C. McPartlin, et al. Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion Clin. Chem., January 1, 2004; 50(1): 3 - 32. [Abstract] [Full Text] [PDF]
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A.-L. B. Monsen, H. Refsum, T. Markestad, and P. M. Ueland Cobalamin Status and Its Biochemical Markers Methylmalonic Acid and Homocysteine in Different Age Groups from 4 Days to 19 Years Clin. Chem., December 1, 2003; 49(12): 2067 - 2075. [Abstract] [Full Text] [PDF]
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R. Clarke, H. Refsum, J. Birks, J. G. Evans, C. Johnston, P. Sherliker, P. M Ueland, J. Schneede, J. McPartlin, E. Nexo, et al. Screening for vitamin B-12 and folate deficiency in older persons Am. J. Clinical Nutrition, May 1, 2003; 77(5): 1241 - 1247. [Abstract] [Full Text] [PDF]
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H. M. Blanck, B. A. Bowman, G. R. Cooper, G. L. Myers, and D. T. Miller Laboratory Issues: Use of Nutritional Biomarkers J. Nutr., March 1, 2003; 133(3): 888S - 894. [Abstract] [Full Text] [PDF]
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N.D. Prins, T. den Heijer, A. Hofman, P.J. Koudstaal, J. Jolles, R. Clarke, and M.M.B. Breteler Homocysteine and cognitive function in the elderly: The Rotterdam Scan Study Neurology, November 12, 2002; 59(9): 1375 - 1380. [Abstract] [Full Text] [PDF]
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N. Q. Hanson, J. H. Eckfeldt, K. Schwichtenberg, O. Aras, and M. Y. Tsai Interlaboratory Variation of Plasma Total Homocysteine Measurements: Results of Three Successive Homocysteine Proficiency Testing Surveys Clin. Chem., September 1, 2002; 48(9): 1539 - 1545. [Abstract] [Full Text] [PDF]
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P. S. Sachdev, M. Valenzuela, X. L. Wang, J. C.L. Looi, and H. Brodaty Relationship between plasma homocysteine levels and brain atrophy in healthy elderly individuals Neurology, May 28, 2002; 58(10): 1539 - 1541. [Abstract] [Full Text] [PDF]
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 E. Hogervorst, H. M. Ribeiro, A. Molyneux, M. Budge, and A. D. Smith Plasma Homocysteine Levels, Cerebrovascular Risk Factors, and Cerebral White Matter Changes (Leukoaraiosis) in Patients With Alzheimer Disease Arch Neurol, May 1, 2002; 59(5): 787 - 793. [Abstract] [Full Text] [PDF]
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N. L. Duarte, X. L. Wang, and D. E. L. Wilcken Effects of Anticoagulant and Time of Plasma Separation on Measurement of Homocysteine Clin. Chem., April 1, 2002; 48(4): 665 - 668. [Full Text] [PDF]
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D. M Kerins, M. J Koury, A. Capdevila, S. Rana, and C. Wagner Plasma S-adenosylhomocysteine is a more sensitive indicator of cardiovascular disease than plasma homocysteine Am. J. Clinical Nutrition, December 1, 2001; 74(6): 723 - 729. [Abstract] [Full Text]
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 A.-L. B. Monsen, P. M. Ueland, S. E. Vollset, A. B. Guttormsen, T. Markestad, E. Solheim, and H. Refsum Determinants of Cobalamin Status in Newborns Pediatrics, September 1, 2001; 108(3): 624 - 630. [Abstract] [Full Text] [PDF]
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M. C. McKinley, J.J. Strain, J. McPartlin, J. M. Scott, and H. McNulty Plasma Homocysteine Is Not Subject to Seasonal Variation Clin. Chem., August 1, 2001; 47(8): 1430 - 1436. [Abstract] [Full Text] [PDF]
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R. Clarke Prevention of vitamin B-12 deficiency in old age Am. J. Clinical Nutrition, February 1, 2001; 73(2): 151 - 152. [Full Text] [PDF]
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 J. C. Chambers, P. M. Ueland, M. Wright, C. J. Dore, H. Refsum, and J. S. Kooner Investigation of Relationship Between Reduced, Oxidized, and Protein-Bound Homocysteine and Vascular Endothelial Function in Healthy Human Subjects Circ. Res., July 20, 2001; 89(2): 187 - 192. [Abstract] [Full Text] [PDF]
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