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Nutrition |
1 Department of Clinical Biochemistry, AKH, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus C, Denmark.
aAuthor for correspondence. Fax 45-89493060; e-mail vakurbor{at}hotmail.com.
Background: We evaluated whether measurement of vitamin B12-saturated transcobalamin (holo-TC) concentrations or TC saturation (holo-TC:total TC) reflects active vitamin B12 absorption in healthy individuals and patients after vitamin B12 intake.
Methods: We obtained blood samples from 31 healthy individuals (age range, 25–57 years) before (days –1 and 0) and after (days 1, 2, and 6) oral administration of three 9-µg doses of vitamin B12. The blood samples from seven patients (age range, 22–39 years) suspected to have decreased vitamin B12 absorption were obtained before and 1 day after the vitamin B12 intake. The blood samples were analyzed for vitamin B12, total TC, and holo-TC. The TC saturation was calculated.
Results: Intraindividual variation was <13% for all measured values, as calculated from samples removed on day –1 and 0. In healthy individuals (n = 31) after intake of vitamin B12, the maximum median (range) increase (as percentages and absolute values) was in TC saturation [52 (–2% to 128)% and 0.04 (0–0.23) as a fraction], closely followed by holo-TC concentrations [39 (0–108)% and 34 (0–149) pmol/L]. All but one healthy individual had an increase of 
15% in these markers. Serum vitamin B12 showed a smaller increase [14 (–8 to 51)% and 36 (–27 to 290) pmol/L]. After vitamin B12 intake, three patients with Crohn disease had the lowest increases in holo-TC concentration (3, 7, and 14 pmol/L) and in TC saturation (0.004, 0.01, and 0.01) among patients and 30 healthy individuals.
Conclusion: Holo-TC concentrations and TC saturation reflect normal vitamin B12 absorption better than does serum vitamin B12.
The following articles in journals at HighWire Press have cited this article:
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  L M L de Lau, A D Smith, H Refsum, C Johnston, and M M B Breteler Plasma vitamin B12 status and cerebral white-matter lesions J. Neurol. Neurosurg. Psychiatry, February 1, 2009; 80(2): 149 - 157. [Abstract] [Full Text] [PDF]
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 A D. Smith and H. Refsum Vitamin B-12 and cognition in the elderly Am. J. Clinical Nutrition, February 1, 2009; 89(2): 707S - 711S. [Abstract] [Full Text] [PDF]
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 M. Vakur Bor, M. Cetin, S. Aytac, C. Altay, P. M. Ueland, and E. Nexo Long term biweekly 1 mg oral vitamin B12 ensures normal hematological parameters, but does not correct all other markers of vitamin B12 deficiency. A study in patients with inherited vitamin B12 deficiency Haematologica, November 1, 2008; 93(11): 1755 - 1758. [Full Text] [PDF]
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 A. Vogiatzoglou, H. Refsum, C. Johnston, S. M. Smith, K. M. Bradley, C. de Jager, M. M. Budge, and A. D. Smith Vitamin B12 status and rate of brain volume loss in community-dwelling elderly Neurology, September 9, 2008; 71(11): 826 - 832. [Abstract] [Full Text] [PDF]
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 M. G. Garrod, R. Green, L. H. Allen, D. M. Mungas, W. J. Jagust, M. N. Haan, and J. W. Miller Fraction of Total Plasma Vitamin B12 Bound to Transcobalamin Correlates with Cognitive Function in Elderly Latinos with Depressive Symptoms Clin. Chem., July 1, 2008; 54(7): 1210 - 1217. [Abstract] [Full Text] [PDF]
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J. Brady, L. Wilson, L. McGregor, E. Valente, and L. Orning Active B12: A Rapid, Automated Assay for Holotranscobalamin on the Abbott AxSYM Analyzer Clin. Chem., March 1, 2008; 54(3): 567 - 573. [Abstract] [Full Text] [PDF]
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K. M von Castel-Roberts, A. L. Morkbak, E. Nexo, C. A Edgemon, D. R Maneval, J. J Shuster, J. F Valentine, G. P. Kauwell, and L. B Bailey Holo-transcobalamin is an indicator of vitamin B-12 absorption in healthy adults with adequate vitamin B-12 status Am. J. Clinical Nutrition, April 1, 2007; 85(4): 1057 - 1061. [Abstract] [Full Text] [PDF]
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 H. Birn The kidney in vitamin B12 and folate homeostasis: characterization of receptors for tubular uptake of vitamins and carrier proteins Am J Physiol Renal Physiol, July 1, 2006; 291(1): F22 - F36. [Abstract] [Full Text] [PDF]
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R. Obeid, A. L. Morkbak, W. Munz, E. Nexo, and W. Herrmann The Cobalamin-Binding Proteins Transcobalamin and Haptocorrin in Maternal and Cord Blood Sera at Birth Clin. Chem., February 1, 2006; 52(2): 263 - 269. [Abstract] [Full Text] [PDF]
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M. V. Bor, E. Lydeking-Olsen, J. Moller, and E. Nexo A daily intake of approximately 6 {micro}g vitamin B-12 appears to saturate all the vitamin B-12-related variables in Danish postmenopausal women Am. J. Clinical Nutrition, January 1, 2006; 83(1): 52 - 58. [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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M. V. Bor, M. Cetin, S. Aytac, C. Altay, and E. Nexo Nonradioactive Vitamin B12 Absorption Test Evaluated in Controls and in Patients with Inherited Malabsorption of Vitamin B12 Clin. Chem., November 1, 2005; 51(11): 2151 - 2155. [Abstract] [Full Text] [PDF]
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