Summary
Definition
History and exam
Key diagnostic factors
- presença de fatores de risco
- idade avançada
- história de cirurgia gástrica (gastrectomia ou bypass gástrico para obesidade)
Other diagnostic factors
- parestesias
- dieta vegana ou vegetariana estrita
- doenças gastrointestinais crônicas (por exemplo, doença de Crohn ou doença celíaca)
- medicamentos (inibidores da bomba de prótons [IBPs], antagonistas do receptor H2, metformina, anticonvulsivantes)
- ataxia
- diminuição da sensibilidade vibratória
- teste de Romberg positivo
- palidez
- petéquias
- glossite
- queilite angular
- comprometimento cognitivo
Risk factors
- idade >65 anos
- cirurgia gástrica (bypass ou ressecção)
- doença gastrointestinal crônica
- dieta vegana ou vegetariana estrita
- uso de metformina
- Uso de antagonistas do receptor H2 ou inibidor da bomba de prótons (IBP)
- infecção por Helicobacter pylori
- uso de anticonvulsivante
- uso indevido de óxido nitroso
- diabetes mellitus
- gestação
Diagnostic investigations
1st investigations to order
- Hemograma completo
- esfregaço de sangue periférico
- vitamina B12 sérica
- contagem de reticulócitos
Investigations to consider
- ácido metilmalônico (AMM)
- homocisteína
- holotranscobalamina (hTC)
- anticorpo anti-fator intrínseco (anti-IFAB)
- anticorpo anticélula parietal (ACP)
- gastrina sérica (em jejum)
Treatment algorithm
pacientes sintomáticos
deficiência assintomática ou limítrofe
Contributors
Authors
Robert C. Oh, MD, MPH, CAQSM

Chief Wellbeing Officer
VA Palo Alto Health Care System
Palo Alto
CA
Divulgaciones
RCO declares that he has no competing interests.
Revisores por pares
Thein Hlaing Oo, MD, FRCP Edin, FACP
Professor of Internal Medicine
Consultant Hematologist
The University of Texas MD Anderson Cancer Center
Houston
TX
Divulgaciones
THO declares that he has no competing interests.
Rebecca Connor, MD
Chief Fellow
Section of Hematology and Oncology
Department of Internal Medicine
Wake Forest University Baptist Medical Center
Winston-Salem
NC
Divulgaciones
RC declares that she has no competing interests.
Peer reviewer acknowledgements
BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.
Disclosures
Peer reviewer affiliations and disclosures pertain to the time of the review.
Referencias
Artículos principales
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.Texto completo Resumen
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.Texto completo Resumen
Stabler SP. Clinical practice. Vitamin B12 deficiency. N Engl J Med. 2013 Jan 10;368(2):149-60. Resumen
National Institutes of Health, Office of Dietary Supplements. Vitamin B12: fact sheet for health professionals. Mar 2024 [internet publication].Texto completo
Guidelines and Protocols Advisory Committee, British Columbia. Cobalamin (vitamin B12) and folate deficiency. Apr 2023 [internet publication].Texto completo
Artículos de referencia
Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.
Diferenciales
- Deficiência de ácido fólico (vitamina B9)
- Síndrome mielodisplásica (SMD)
- Doença hepática relacionada ao álcool
Más DiferencialesGuías de práctica clínica
- Vitamin B12: fact sheet for health professionals
- Vitamin B12 deficiency in over 16s: diagnosis and management
Más Guías de práctica clínicaFolletos para el paciente
Deficiência de vitamina B12
Anorexia
Más Folletos para el pacienteVideos
Venopunção e flebotomia – Vídeo de demonstração
More videosLog in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer