Vitamin B12 deficiency--need for a new guideline

Area of Science:

• Clinical Biochemistry
• Hematology
• Nutritional Science

Background:

• Vitamin B12 deficiency often presents without classic indicators like anemia or macrocytosis.
• The prevalence of vitamin B12 deficiency in patients without these indicators remains largely unknown.
• Accurate identification of vitamin B12 deficiency is crucial for preventing neurological and hematological complications.

Purpose of the Study:

• To determine the prevalence of vitamin B12 deficiency in patients with normocytosis and microcytosis.
• To evaluate the effectiveness of current screening strategies for vitamin B12 deficiency.
• To propose an optimized screening strategy for vitamin B12 deficiency.

Main Methods:

• A retrospective review of 3714 patients with serum vitamin B12 levels measured at Prince of Wales Hospital in 1996.
• Analysis of serum vitamin B12 levels (<140 pmol/L) across various subgroups: age (<70, >70), anemia status, red blood cell indices (macrocytic, normocytic, microcytic), and documented iron deficiency or thalassemia.
• Calculation of prevalence rates for vitamin B12 deficiency within each subgroup.

Main Results:

• The prevalence of vitamin B12 deficiency (<140 pmol/L) varied between 4.8% and 9.8% across the studied patient subgroups.
• A significant proportion of patients with vitamin B12 deficiency were identified within normocytic and microcytic groups.
• Current screening criteria, based on anemia or macrocytosis, are insufficient to identify all cases of vitamin B12 deficiency.

Conclusions:

• Conventional screening methods for vitamin B12 deficiency, relying on anemia or macrocytosis, will miss a substantial number of deficient patients.
• The study highlights the need for a broader screening approach due to the prevalence of deficiency in patients without typical indicators.
• Universal vitamin B12 screening may be a justifiable strategy to ensure timely diagnosis and treatment, thereby preventing associated health issues.