Deficiência de vitamina B12

Níveis séricos de vitamina B12

A probabilidade de deficiência de vitamina B12 pode ser definida de acordo com o nível sérico de vitamina B12 conforme a seguir:[1]Devalia V, Hamilton MS, Molloy AM; British Committee for Standards in Haematology. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. Br J Haematol. 2014 Aug;166(4):496-513. http://onlinelibrary.wiley.com/doi/10.1111/bjh.12959/full http://www.ncbi.nlm.nih.gov/pubmed/24942828?tool=bestpractice.com [2]Snow CF. Laboratory diagnosis of vitamin B12 and folate deficiency: a guide for the primary care physician. Arch Intern Med. 1999 Jun 28;159(12):1289-98. http://archinte.ama-assn.org/cgi/content/full/159/12/1289 http://www.ncbi.nlm.nih.gov/pubmed/10386505?tool=bestpractice.com

• Provável deficiência de vitamina B12: <148 picomoles/L (<200 picogramas/mL)

• Possível deficiência de vitamina B12: 148 a 258 picomoles/L (201 a 350 picogramas/mL)

• Improvável deficiência de vitamina B12: >258 picomoles/L (>350 picogramas/mL).

Um nível de vitamina B12 >258 picomoles/L (>350 picogramas/mL) não descarta deficiência de vitamina B12, sobretudo se houver suspeita de anemia perniciosa. Foram relatados níveis de vitamina B12 sérica falsamente normais ou altos em pacientes com anemia perniciosa em decorrência de interferência de anticorpos anti-fator intrínseco (anti-IFAB) em ensaios laboratoriais.[3]Tavares J, Baptista B, Gonçalves B, et al. Pernicious anaemia with normal vitamin B12. Eur J Case Rep Intern Med. 2019;6(2):001045. https://www.ejcrim.com/index.php/EJCRIM/article/view/1045 http://www.ncbi.nlm.nih.gov/pubmed/30931271?tool=bestpractice.com [4]Shah DR, Daver N, Borthakur G, et al. Pernicious anemia with spuriously normal vitamin B12 level might be misdiagnosed as myelodysplastic syndrome. Clin Lymphoma Myeloma Leuk. 2014 Aug;14(4):e141-3. http://www.ncbi.nlm.nih.gov/pubmed/24630920?tool=bestpractice.com [5]Yang DT, Cook RJ. Spurious elevations of vitamin B12 with pernicious anemia. N Engl J Med. 2012 May 3;366(18):1742-3. https://www.nejm.org/doi/full/10.1056/NEJMc1201655 http://www.ncbi.nlm.nih.gov/pubmed/22551146?tool=bestpractice.com [6]Mazokopakis EE. Normal serum cobalamin levels do not exclude the diagnosis of pernicious anaemia: a case report. Fam Pract. 2020 Feb 19;37(1):1-3. https://academic.oup.com/fampra/article/37/1/1/5709531 http://www.ncbi.nlm.nih.gov/pubmed/31953947?tool=bestpractice.com