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

ABSTRACT

BACKGROUND: Hemolytic features in patients with pernicious anemia have not been emphasized. METHODS: Seven Japanese patients at 60 - 88 years of age with vitamin B12 deficiency-related hemolytic anemia were assessed. RESULTS: 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. CONCLUSIONS: In elderly patients exhibiting hemolytic features in association with macrocytic anemia, vitamin B12 deficiency should be considered in the differential diagnosis.