Screening

Screening is controversial, but clinicians should take certain risk factors into account when considering testing for vitamin B12 deficiency.

  • Advancing age: increased risk for vitamin B12 deficiency.[11][12][13][14][15][16]

  • Chronic use of certain medications: metformin, proton-pump inhibitors, and anticonvulsants can place a patient at risk of deficiency.[31][32][37][38][49][50][51][52]

  • Malnutrition and vegan or strict vegetarian diet: increased risk of vitamin deficiency, and serum vitamin level monitoring may be offered.[26][48]

  • Chronic gastrointestinal illness: can cause malabsorption or inadequate absorption (e.g., Crohn's disease, coeliac disease).​​[46][47]

  • Gastric surgery (bypass or resection): high risk of vitamin B12 deficiency due to inadequate absorption.[27][45] Patients who have undergone gastric surgery or terminal ileectomy should be screened regularly for deficiency.[27][45][46][47][74]

  • Diabetic polyneuropathy (DPN), or worsening DPN: may be at increased risk for concomitant vitamin B12 deficiency.[80]

  • Peripheral neuropathy (idiopathic): patients may be at increased risk for concomitant vitamin B12 deficiency.[7]

A two to threefold excess risk of gastric cancer has been noted in patients with pernicious anaemia, and endoscopic follow-up may be required in these patients.[81]

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