What are the recommended treatment protocols for vitamin B12 deficiency in patients with pernicious anemia?

For patients diagnosed with pernicious anemia, the recommended treatment protocol is to offer lifelong intramuscular vitamin B12 replacement, specifically hydroxocobalamin 1 mg intramuscularly every 2–3 months for life, as the deficiency is considered an irreversible cause of vitamin B12 deficiency ¹.

Alternatively, daily large oral doses of vitamin B12 (500 to 1000 micrograms) can be considered for maintenance therapy, especially if injections are not tolerated, but clinical judgment is advised due to absorption issues in pernicious anemia ³.

Initial treatment for suspected or confirmed deficiency caused by autoimmune gastritis or pernicious anemia should involve parenteral therapy, with expert opinion supporting the use of B12 injections to rapidly correct deficiency, particularly in cases with neurological symptoms ⁴.