# B12 Deficiency-Induced Hemolytic Anemia With an Extensive Deep Vein Thrombosis

## TL;DR

A patient with severe B12 deficiency developed life-threatening blood disorders and a deep vein clot, highlighting the importance of early detection and treatment.

## Contribution

This case emphasizes the rare but severe complications of B12 deficiency, including hemolytic anemia and extensive DVT.

## Key findings

- B12 deficiency was linked to hemolytic anemia, pancytopenia, and DVT in a 56-year-old woman.
- The patient had elevated methylmalonic acid, low haptoglobin, and a positive intrinsic factor antibody.
- Treatment included B12 injections and anticoagulation, underscoring the need for prompt management.

## Abstract

Vitamin B12 deficiency is a commonly encountered condition in both inpatient and outpatient settings. However, in severe cases, it can have many hematologic complications that can be life-threatening. We present a 56-year-old African American female patient presenting with fatigue found to have a B12 deficiency with elevated methylmalonic levels with simultaneous hemolytic anemia, pancytopenia, and an extensive deep vein thrombosis (DVT) involving her lower extremities. Labs showed anemia, thrombocytopenia, macrocytosis, elevated lactate dehydrogenase (LDH), low haptoglobin, elevated D-dimer, and a positive intrinsic factor blocking antibody leading to a diagnosis of pernicious anemia. Along with anticoagulation, the patient was recommended intramuscular B12 injections daily for seven days followed by weekly and then monthly. Here, we emphasize that B12 deficiency can be life-threatening and requires a high index of suspicion for early recognition of various downstream effects for appropriate management and treatment.