Hemolytic Anemia and Pancytopenia Secondary to Vitamin B12 Deficiency: Evaluation and Clinical Significance.

Severe vitamin B12 deficiency presents a diagnostic challenge due to its diverse clinical manifestations, which can mimic serious hematologic disorders such as thrombotic thrombocytopenic purpura (TTP) or leukemia. The case we present here illustrates the unique characteristics of severe B12 deficiency, highlighting key differentiators from other conditions, including decreased reticulocyte counts and markedly elevated lactate dehydrogenase levels indicative of suppressed erythropoiesis. Advanced cobalamin deficiency affects all cell lines, leading to peripheral pancytopenia. Proposed mechanisms include fragile red blood cells prone to shearing, resulting in schistocyte formation, and hyperhomocysteinemia-induced oxidative stress exacerbating hemolysis. Prompt recognition and treatment with B12 replacement are critical, as illustrated by this case of hemolytic anemia and pancytopenia secondary to pernicious anemia, to prevent severe hematologic complications.