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Vitamin B12 deficiency

Key sources
The following summarized guidelines for the evaluation and management of vitamin B12 deficiency are prepared by our editorial team based on guidelines from the American Diabetes Association (ADA 2023), the European Association of Urology (EAU 2023), the Italian Society of Digestive Endoscopy (SIDE/SIGE 2022), the European Association for the Study of the Liver (EASL 2022), the European Society for Radiotherapy and Oncology (ESTRO/EACTS/ERS/ESTS 2020), the Kidney Disease: Improving Global Outcomes Foundation (KDIGO 2020; 2012), the American Society of Anesthesiologists (ASA/ACE/OS/AACE/ASMBS/OMA 2020), the British Society of Gastroenterology (BSG 2019), the European Society for the Study of Coeliac Disease (ESsCD 2019), the European Academy of Dermatology and Venereology (EADV/UEMS/EFA/ETFAD/EDF/EAACI/ESDaP/ESPD 2018), the National Comprehensive Cancer Network (NCCN 2018), the American Academy of Family Physicians (AAFP 2017), the Maastricht V/Florence Consensus Report (Maastricht V/Florence 2017), the American Society for Metabolic and Bariatric Surgery (ASMBS 2017), the European Association for the Study of Obesity (EASO 2017), the United Kingdom Kidney Association (UKKA 2017), the British Society for Haematology (BSH 2017; 2014), the Society of Critical Care Medicine (SCCM/ASPEN 2016), the Endocrine Society (ES 2016), the Society for Vascular Surgery (SVS 2015), the American Academy of Sleep Medicine (AASM 2015), the European Crohn's and Colitis Organisation (ECCO 2015), the American Heart Association (AHA/ACC 2014), the American Academy of Dermatology (AAD 2014), the American College of Endocrinology (ACE/OS/AACE 2013), the Obesity Society (OS/AACE 2013), the American College of Gastroenterology (ACG 2013), the American Society for Parenteral and Enteral Nutrition (ASPEN 2013), the European Federation of Neurological Societies (EFNS 2010), and the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM/AAN 2009).
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Guidelines

1.Screening and diagnosis

Indications for screening, general principles: obtain screening with a CBC and serum vitamin B12 level measurement in patients with risk factors for vitamin B12 deficiency.
B
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  • Indications for screening (elderly patients)

  • Indications for screening (vegetarians)

  • Indications for screening (patients on metformin)

  • Indications for screening (IBD)

  • Indications for screening (CKD)

  • Indications for screening (polyneuropathy)

  • Indications for screening (pre-bariatric surgery)

  • Indications for screening (post-bariatric surgery)

  • Indications for screening (post-radical cystectomy)

  • Indications for screening (primary adrenal insufficiency)

  • Indications for screening (hematological disorders)

  • Diagnostic criteria

2.Diagnostic investigations

Serum vitamin B12 and folate: assess serum vitamin B12 and folate levels in patients with suspected vitamin B12 deficiency.
A

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  • Serum homocysteine and MMA

  • Serum holotranscobalamin

  • Evaluation for pernicious anemia

  • Screening for H. pylori infection (Maastricht V/Florence)

  • Screening for H. pylori infection

  • Screening for gastric cancer

3.Medical management

Vitamin B12 supplementation, without neurological involvement, AAFP: administer oral or injectable preparations for vitamin B12 replacement recognizing that injectable therapy leads to more rapid improvement. Consider administering injectable vitamin B12 preparations in patients with severe vitamin B12 deficiency.
B

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  • Vitamin B12 supplementation (with neurological involvement)

4.Specific circumstances

Pediatric patients: treat vitamin B12 deficiency promptly in infants to prevent long-term neurological sequelae.
A

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  • Pregnant patients

  • Patients on metformin

  • Patients on hormone therapy

  • Patients with pernicious anemia

  • Patients with chronic liver disease

  • Patients with found-bound cobalamin malabsorption

5.Preventative measures

Prophylactic vitamin B12 supplementation, post-bariatric surgery, AAFP: initiate oral vitamin B12 supplementation (1 mg/day) and continue indefinitely in patients post-bariatric surgery.
B

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  • Prophylactic vitamin B12 supplementation (patients on pemetrexed)

  • Prophylactic vitamin B12 supplementation (patients on metformin)

  • Prophylactic vitamin B12 supplementation (CVD)

  • Prophylactic vitamin B12 supplementation (PAD)

  • Prophylactic vitamin B12 supplementation (atopic dermatitis)

  • Prophylactic vitamin B12 supplementation (sleep-wake disorder)