Thrombotic Microangiopathy-Like Hemolysis in Vitamin B12 Deficiency-Related Macrocytic Anemia

Hemolytic features in patients with pernicious anemia have not been emphasized.

Seven Japanese patients at 60 - 88 years of age with vitamin B12 deficiency-related hemolytic anemia were assessed.

Serum vitamin B12 levels in these cases were 46 - 89 pg/mL (normal reference range: 233 - 914 pg/mL). Clinically, the patients presented with thrombotic microangiopathy (TMA)-like hemolytic features (including macrocytic anemia, schistocytes on blood smears, high serum lactate dehydrogenase, hyperbilirubinemia, and low serum haptoglobin). Six cases had type A gastritis (assessed by esophagogastroduodenoscopy with hypergastrinemia) with additional laboratory data of high plasma homocysteine levels and anti-intrinsic factor/anti-parietal cell antibodies. One case was in post-gastrectomy condition. Following treatment with vitamin B12, anemia resolved within 4 weeks in five of the seven cases except for two cases of delayed response.

In elderly patients exhibiting hemolytic features in association with macrocytic anemia, vitamin B12 deficiency should be considered in the differential diagnosis.