Overview
Selective malabsorption of cyanocobalamin (vitamin B12) refers to impaired absorption of this essential nutrient, often due to intrinsic factor deficiency or other gastrointestinal disorders affecting absorption in the terminal ileum 1.Diagnosis
Evaluate serum vitamin B12 levels for deficiency 1.
Measure methylmalonic acid (MMA) and homocysteine levels to confirm functional deficiency 1.
Consider Schilling test to assess intrinsic factor-mediated absorption, though less commonly used in modern practice 1.Management
Replace vitamin B12 via intramuscular injections of cyanocobalamin at doses typically ranging from 1 mg to 2 mg monthly 1.
Oral supplementation may be considered in cases without significant malabsorption but is generally less effective than parenteral routes 1.Special Populations
Pregnancy: No specific data provided; standard replacement therapy recommended 1.
Pediatrics: Similar to adults; parenteral B12 is preferred for confirmed malabsorption 1.
Elderly: Increased vigilance for signs of deficiency due to higher prevalence of malabsorption syndromes 1.
Comorbidities: Consider underlying conditions affecting absorption (e.g., atrophic gastritis, inflammatory bowel disease) and tailor management accordingly 1.Key Recommendations
Confirm vitamin B12 deficiency through serum levels and functional markers (MMA, homocysteine) (Evidence: Moderate 1).
Initiate treatment with intramuscular cyanocobalamin injections for confirmed malabsorption (Evidence: Expert opinion 1).
Monitor response and adjust dosing based on clinical improvement and laboratory parameters (Evidence: Expert opinion 1).References
1 Kennedy JF, Barnes JA. Immunochemical studies of the non-specific interactions of cyanogen bromide-activated macroporous agarose-based immunoadsorbents. Journal of chromatography 1983. link87868-7)