[Vitamin B12 deficiency: what's new?].

Area of Science:

• Internal Medicine
• Clinical Chemistry
• Gastroenterology

Context:

• Vitamin B12 deficiency diagnosis and management.
• Screening guidelines for vitamin B12 deficiency.
• Role of holotranscobalamin as a biomarker.

Purpose:

• To review the current recommendations and challenges in Vitamin B12 deficiency screening and management.
• To highlight the utility of holotranscobalamin over cyanocobalamin in specific clinical scenarios.
• To discuss the importance of excluding autoimmune gastritis and the considerations for oral substitution therapy.

Summary:

• Vitamin B12 screening is typically reserved for symptomatic patients or those with identified risk factors.
• Food cobalamin malabsorption syndrome is the primary etiology of vitamin B12 deficiency.
• Holotranscobalamin is presented as a more dependable marker for confirming vitamin B12 deficiency compared to cyanocobalamin, though its validation in complex cases is pending.
• Autoimmune gastritis should be investigated in cases of probable deficiency without apparent risk factors.
• Oral vitamin B12 substitution is effective but necessitates strict patient adherence and careful monitoring for treatment response.
• The efficacy of oral substitution has not been evaluated in patients with severe symptoms, inflammatory bowel disease, or following ileal resection.

Impact:

• Provides an updated perspective on vitamin B12 deficiency diagnosis and treatment.
• Emphasizes the clinical utility of holotranscobalamin testing.
• Guides clinical decision-making regarding screening, differential diagnosis, and therapeutic strategies for vitamin B12 deficiency.