Vitamin B12 deficiency remains a significant cause of hematologic and neurologic morbidity globally. Therefore, clinicians must prioritize a prompt pernicious anemia diagnosis to prevent irreversible damage. This condition often stems from an autoimmune lack of intrinsic factor. Recently, a retrospective study analyzed 270 adults at a Mexican tertiary center to clarify its etiologic spectrum.

Furthermore, researchers found that pernicious anemia was the most frequent etiology, accounting for 52.6% of cases. In contrast, non-surgical malabsorption and post-surgical states were less common. Consequently, understanding these patterns is crucial for effective management in specialized clinics. Notably, the clinical severity was significantly higher in patients with pernicious anemia than in those with other causes.

Improving the Pernicious Anemia Diagnosis

However, the study also revealed a significant diagnostic pitfall regarding red cell indices. Many patients with non-pernicious etiologies showed a median mean corpuscular volume (MCV) within the normocytic range. This finding suggests that a pernicious anemia diagnosis or a general evaluation for B12 deficiency should not depend on macrocytosis alone. Patients with pernicious anemia generally presented with lower hemoglobin and lower vitamin B12 levels. Despite these differences, symptoms like weight loss and neurologic alterations remained common across all groups. Thus, clinicians should maintain a high index of suspicion even in the absence of classic hematologic markers.

FAQs on B12 Deficiency and Pernicious Anemia

What is the primary cause of Vitamin B12 deficiency in tertiary care settings?

According to recent cohort data, pernicious anemia is the leading cause, often associated with greater hematologic and biochemical severity compared to other etiologies.

Can Vitamin B12 deficiency occur without an increased MCV?

Yes. Many patients, particularly those with non-pernicious causes, present with normocytic indices. Therefore, overreliance on macrocytosis can delay a diagnosis and subsequent treatment.

Disclaimer: This content is for informational and educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

Moreno-Mirón JM et al. Pernicious anemia predominates among Mexican adults with vitamin B12 deficiency: clinical and laboratory findings from a tertiary referral center. Rev Invest Clin. 2026 May 25. doi: undefined. PMID: 42184486.

Stabler SP. Vitamin B12 Deficiency. N Engl J Med. 2013;368(2):149-160.

Green R. Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood. 2017;129(19):2603-2611.