Clinicians need to consider analytical issues when requesting and interpreting these tests
Vitamin B12 and folate tests are useful for identifying patients with a deficiency. In this issue of the Journal, Willis and colleagues highlight some of the limitations of serum vitamin B12 assays.1 They also emphasise the uncertainty regarding whether red-cell or serum folate should be the preferred first-line test for folate status. The issues underlying some of the data presented require elaboration.
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- 1. Willis CD, Metz MP, Hiller JE, Elshaug AG. Vitamin B12 and folate tests: the ongoing need to determine appropriate use and public funding. Med J Aust 2013; 198: 586-588
- 2. Green R. Indicators for assessing folate and vitamin B12 status and for monitoring the efficacy of intervention strategies. Food Nutr Bull 2008; 29 (2 Suppl): S52-S63.
- 3. Valente E, Scott JM, Ueland PM, et al. Diagnostic accuracy of holotranscobalamin, methylmalonic acid, serum cobalamin, and other indicators of tissue vitamin B12 status in the elderly. Clin Chem 2011; 57: 856-863.
- 4. Pennypacker LC, Allen RH, Kelly JP, et al. High prevalence of cobalamin deficiency in elderly outpatients. J Am Geriatr Soc 1992; 40: 1197-1204.
- 5. Carmel R, Agrawal YP. Failures of cobalamin assays in pernicious anemia. N Engl J Med 2012; 367: 385-386.
- 6. Hamilton MS, Blackmore S, Lee A. Possible cause of false normal B-12 assays. BMJ 2006; 333: 654-655.
- 7. Farrell CJ, Kirsch SH, Herrmann M. Red cell or serum folate: what to do in clinical practice? Clin Chem Lab Med 2013; 51: 555-569.
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