Last reviewed: June 2020
Last updated: November  2019

Summary

Definition

History and exam

Key diagnostic factors

  • old age
  • history of gastric surgery (gastrectomy, or bypass for obesity)

Other diagnostic factors

  • paresthesias
  • vegan and strict vegetarian diet
  • chronic gastrointestinal disease (e.g., Crohn disease or celiac disease)
  • medication (proton-pump inhibitors, H2 receptor antagonists, metformin, anticonvulsants)
  • ataxia
  • decreased vibration sense
  • positive Romberg test
  • pallor
  • petechiae
  • glossitis
  • angular cheilitis
  • cognitive impairment

Risk factors

  • age >65 years
  • gastric surgery (bypass or resection)
  • chronic gastrointestinal (GI) disease
  • vegan diet
  • metformin use
  • H2 receptor antagonist or proton-pump inhibitor use
  • Helicobacter pylori infection
  • anticonvulsant use
  • diabetes mellitus
  • pregnancy

Diagnostic investigations

1st investigations to order

  • CBC
  • peripheral blood smear
  • serum vitamin B12
  • reticulocyte count
More 1st investigations to order

Investigations to consider

  • methylmalonic acid (MMA)
  • homocysteine
  • holotranscobalamin
  • intrinsic factor (IF) antibody
  • antiparietal cell (APC) antibody
  • serum gastrin (fasting)
  • Schilling test
More investigations to consider

Treatment algorithm

Contributors

Robert C. Oh

Director

Faculty Development Fellowship

Madigan Army Medical Center

Tacoma

WA

Disclosures

RCO declares that he has no competing interests.

Peer reviewersVIEW ALL

Chief Fellow

Section of Hematology and Oncology

Department of Internal Medicine

Wake Forest University Baptist Medical Center

Winston-Salem

NC

Disclosures

RC declares that she has no competing interests.

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