This protocol applies to patients with Vitamin B12 deficiency anemia where the underlying cause is impaired absorption — specifically when B12 deficiency is secondary to a suspected or confirmed diagnosis of pernicious anaemia, autoimmune gastritis, total gastrectomy, or complete terminal ileal resection.
In this population, B12 deficiency arises from malabsorption rather than dietary insufficiency. The underlying conditions — pernicious anaemia, autoimmune gastritis, total gastrectomy, or complete terminal ileal resection — each impair the body's ability to absorb vitamin B12 through the gastrointestinal tract, making standard oral supplementation inadequate.
Management centres on a structured hydroxocobalamin replacement regimen, involving a defined loading period followed by ongoing long-term maintenance. Self-administration is encouraged where feasible. Oral supplementation is not the recommended route in this population. Dietary guidance forms part of the overall plan. The complete delivery method, schedule, and maintenance interval are detailed in the full protocol.
Symptoms may begin to improve within 2 weeks, with full improvement taking up to 3 months — patients should be counselled that symptoms may initially worsen before recovering. A prompt rise in haemoglobin level is an expected marker of an adequate treatment response.