Rao Swathi, Colon Hidalgo Daniel, Doria Medina Sanchez Jorge A, Navarrete Deyger, Berg Stephanie
Internal Medicine, MacNeal Hospital, Berwyn, USA.
Nephrology, Los Angeles County+USC Medical Center, Los Angeles, USA.
Cureus. 2020 Jul 9;12(7):e9097. doi: 10.7759/cureus.9097.
Vitamin B12 deficiency is classically associated with megaloblastic anemia. Possible cobalamin deficiency is not investigated once hemolysis is seen. Around 2.5% of cases can present as pseudo-thrombotic microangiopathy (TMA). A swift identification of this means the difference between an easy solution and a protracted one for the patient. A 74-year-old man with no past medical history presented with exertional dyspnea, fatigue, and increasing anorexia over two weeks. Physical examination including a neurological examination was normal. Laboratory tests revealed pancytopenia, unconjugated hyperbilirubinemia, elevated LDH (lactate dehydrogenase), low haptoglobin, and fragmented red blood cells (RBCs) on the peripheral smear, but normal FDP (fibrinogen degradation product) and fibrinogen. The absolute reticulocyte count was reduced as opposed to the expected elevation. Vitamin B12 levels were undetectable, and severe cobalamin deficiency from pernicious anemia was found to be the paramount etiology. Cobalamin deficiency causing pseudo-TMA baffles most physicians. Advanced pernicious anemia is thought to cause intramedullary hemolysis, resulting in peripheral pancytopenia. The fragile RBCs are easily sheared, producing schistocytosis without platelet microthrombi. In contrast to hemolytic anemias, reticulocyte count is low given the unavailability of B12 for erythropoiesis. Reticulocytopenia is a universal finding in cases of pseudo-TMA. Around 38.8% of cases with pseudo-TMA are misdiagnosed as thrombotic thrombocytopenic purpura and treated with plasma product therapy. Keeping an eye out for reticulocytopenia in cases of hemolysis could mean a world of difference for the patient.
维生素B12缺乏症通常与巨幼细胞贫血相关。一旦出现溶血，就不会对可能存在的钴胺素缺乏进行调查。约2.5%的病例可表现为假性血栓性微血管病（TMA）。迅速识别这一点意味着患者的治疗方案是简单还是漫长的区别。一名74岁男性，无既往病史，在两周内出现劳力性呼吸困难、疲劳和食欲减退。包括神经系统检查在内的体格检查正常。实验室检查显示全血细胞减少、非结合胆红素血症、乳酸脱氢酶（LDH）升高、触珠蛋白降低，外周血涂片可见破碎红细胞（RBC），但纤维蛋白原降解产物（FDP）和纤维蛋白原正常。绝对网织红细胞计数降低，与预期升高相反。维生素B12水平检测不到，发现恶性贫血导致的严重钴胺素缺乏是首要病因。钴胺素缺乏导致的假性TMA使大多数医生感到困惑。晚期恶性贫血被认为会导致髓内溶血，从而导致外周全血细胞减少。脆弱的红细胞很容易被剪切，产生裂红细胞症而无血小板微血栓形成。与溶血性贫血不同，由于缺乏用于红细胞生成的维生素B12，网织红细胞计数较低。网织红细胞减少是假性TMA病例的普遍表现。约38.8%的假性TMA病例被误诊为血栓性血小板减少性紫癜并接受血浆制品治疗。在溶血病例中留意网织红细胞减少对患者来说可能意义重大。
