Etiology

Deficiency may be due to:

  • Defective vitamin B12 absorption, e.g. in pernicious anemia or certain drug therapies that cause low intrinsic factor production.
  • Bacterial overgrowth of the GI tract that uses up vitamin B12 [GP2008].
  • Genetic mutations in B12 transporter proteins may result in a functional intracellular deficiency of vitamin B12, despite adequate serum levels of vitamin B12 [PA-OAT], [Surendran2018  🕮 ].

Diagnosis

Symptoms of Vitamin B12 deficiency include:

Tests include:

References