A RARE CASE OF PSEUDO-TMA IN A PATIENT WITH COBALAMIN DEFICIENCY S Surapaneni MD, P Ellipeddi MD Department of Medicine, Baton Rouge General Medical Center, Baton Rouge LA INTRODUCTION Pseudo-thrombotic microangiopathy (pseudo-TMA) is a very uncommon, clinical presentation of vitamin B12 deficiency. Patients with severe vitamin B12 deficiency may present with features mimicking thrombotic thrombocytopenic purpura (TTP) such as microangiopathic hemolytic anemia, thrombocytopenia and schistocytosis. Primary TMA syndromes include TTP, Hemolytic Uremic Syndrome, drug induced TMA, and complement-mediated TMA. Pseudo-TMA responds to vitamin B12 replacement whereas Primary TMA requires plasmapheresis or monoclonal antibody therapy. CASE: A 55-year-old woman presented with 5-day history of sluggishness and profound fatigue. A complete blood count showed macrocytic anemia, thrombocytopenia and leukopenia. Hemoglobin was 5.4 g/dL, MCV was 102 FL, platelets were 72,000/ MCL and WBC count was 3,820/MCL. Work-up revealed severe vitamin B12 deficiency at <60 pg/mL and hemolysis. Indirect bilirubin was increased at 1.3 mg/dL, LDH was increased at >4000 Unit/L, haptoglobin was decreased at <8 mg/dL, and negative direct antiglobulin test. Her reticulocyte percent was 1.8% (0.5–2.5%), suggesting suboptimal bone marrow response. Peripheral blood smear showed schistocytes and hyper segmented neutrophils. The patient was afebrile, and her creatinine was slightly elevated at 1.24. Given the presence of hemolysis, thrombocytopenia and schistocytosis, the diagnosis of TTP was a concern and therefore ADAMTS13 activity, was obtained. Vitamin B12 (1000 mcg IM daily) was initiated. Over the next 3 days, the patient’s hemoglobin and platelets stabilized. On day 5, ADAMTS13 activity came back normal at 92%. Accordingly, parenteral B12 replacement was continued which resulted in cessation of hemolysis and normalization of hemoglobin and platelets. Finally, the parietal cell autoantibodies came back positive consistent with pernicious anemia. DISCUSSION: Pseudo-TMA can be experienced in 2.5% of patients with cobalamin deficiency. When TTP is suspected plasma exchange should be initiated immediately. Pseudo-TMA with cobalamin deficiency does not respond to plasma exchange and require B12 replacement. An early and accurate diagnosis is important to avoid unnecessary, ineffective and potentially harmful therapy.
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