PDF(Pubmed)
Abstract：
While macrocytic anemia is common in vitamin B12 deficiency, rarely, pancytopenia and hemolytic anemia can occur. Homocysteine levels are elevated in severe B12 deficiency, and this is linked to thrombus formation with potentially life-threatening complications. We present a patient with severe vitamin B12 deficiency complicated by hyperhomocysteinemia and obstructive shock from pulmonary embolism. A 56-year-old male with no medical history presented to the hospital with altered mentation. The patient\'s family stated he was experiencing bilateral paresthesias of his lower extremities, progressive depression, anxiety, and insomnia. Initial vitals were blood pressure of 76/36, heart rate of 70 beats per minute, respiratory rate of 14, and temperature of 36.3 degrees Celsius. He was intubated due to severe encephalopathy. Relevant labs indicated severe macrocytic anemia, thrombocytopenia, decreased B12 levels, elevated methylmalonic acid, and elevated homocysteine. Imaging demonstrated a right common femoral vein thrombosis and subsegmental pulmonary emboli. Peripheral blood smear revealed schistocytes, anisopoikilocytosis, and decreased platelet count. The patient required fluid resuscitation, antibiotics, and multiple blood products. Vitamin B12 was administered intramuscularly, which improved the anemia. Esophagogastroduodenoscopy (EGD) demonstrated gastritis. Gastric and duodenal biopsies were negative for Helicobacter pylori and celiac disease. He was negative for intrinsic factor (IF) antibodies but had elevated gastrin levels. An intravenous unfractionated heparin infusion was started when the platelet count was above 50000. The patient was extubated after seven days. Heparin was transitioned to apixaban and an inferior vena cava (IVC) filter was placed. Hyperhomocysteinemia is a known pro-thrombotic factor that can lead to the development of venous thromboembolism. B12 malabsorption can stem from inflammatory bowel disease, celiac disease, gastritis, pancreatic insufficiency, gastrectomy, gastric bypass surgery, or antibodies to IF. While this case showed gastritis and negative IF antibodies, gastrin levels were elevated, indicating a mixed picture. This highlights the challenge of definitively diagnosing pernicious anemia as the cause of vitamin B12 deficiency. Vitamin B12 deficiency may lead to critical illness in which thromboembolism develops secondary to hyperhomocysteinemia.
摘要：
虽然大细胞性贫血在维生素B12缺乏中很常见，很少,可发生全血细胞减少和溶血性贫血。在严重的B12缺乏症中，同型半胱氨酸水平升高，这与血栓形成和潜在危及生命的并发症有关.我们介绍了一名患有严重维生素B12缺乏症并伴有高同型半胱氨酸血症和肺栓塞引起的阻塞性休克的患者。一名56岁的男性，无病史，因精神改变被送往医院。病人的家人说他下肢感觉异常，进行性抑郁症,焦虑,和失眠。最初的重要指标是血压为76/36，心率为每分钟70次，呼吸频率为14，温度为36.3摄氏度。他因严重脑病而插管。相关实验室显示严重的大细胞性贫血,血小板减少症,B12水平下降，甲基丙二酸升高，高半胱氨酸水平升高.影像学显示右侧常见股静脉血栓形成和亚段肺栓塞。外周血涂片显示分裂细胞，异红细胞增多症,血小板计数减少。病人需要液体复苏,抗生素,和多种血液制品。肌肉注射维生素B12，改善了贫血。食管胃十二指肠镜检查（EGD）显示胃炎。胃和十二指肠活检对幽门螺杆菌和乳糜泻均为阴性。他对内在因子（IF）抗体呈阴性，但胃泌素水平升高。当血小板计数高于50000时，开始静脉内普通肝素输注。患者在7天后拔管。将肝素转换为阿哌沙班，并放置下腔静脉（IVC）过滤器。高同型半胱氨酸血症是一种已知的促血栓形成因子，可导致静脉血栓栓塞的发展。B12吸收不良可能源于炎症性肠病，乳糜泻,胃炎,胰腺功能不全,胃切除术,胃旁路手术,或IF抗体。虽然此病例显示胃炎和IF抗体阴性，胃泌素水平升高，表明混合的图片。这凸显了明确诊断恶性贫血为维生素B12缺乏原因的挑战。维生素B12缺乏可能导致严重疾病，其中血栓栓塞继发于高同型半胱氨酸血症。
