Shahani Lokesh, Sattovia Stacy
Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, Illinois, USA.
BMJ Case Rep. 2012 Sep 17;2012:bcr2012006756. doi: 10.1136/bcr-2012-006756.
Methaemoglobin is an altered state of haemoglobin in which the ferrous ions of haeme are oxidised to the ferric state. This results in increased affinity to the bound oxygen and decreasing its availability to tissues. Most cases of methaemoglobinaemia are acquired, resulting from an increased methaemoglobin formation by various exogenous agents. The authors report an elderly patient presenting to the emergency department with a 1-month history of shortness of breath. Around the same time she had started using over-the-counter (OTC) phenazopyridine tablets for urinary symptoms. The patient was hypoxic and cyanotic; however, lacked evidence of hypoxaemia on the arterial blood gas. The presence of abnormal haemoglobin was suspected and confirmed by elevated levels of methaemoglobin. Phenazopyridine was proposed to be the likely aetiology of the methaemoglobinaemia, which the patient was not aware of. This case highlights the importance of always inquiring the OTC drug use especially in geriatric population.
高铁血红蛋白是血红蛋白的一种改变状态，其中血红素的亚铁离子被氧化为铁离子状态。这导致对结合氧的亲和力增加，并降低其向组织的可用性。大多数高铁血红蛋白血症病例是后天获得的，由各种外源性物质导致高铁血红蛋白形成增加引起。作者报告了一名老年患者因气短1个月到急诊科就诊。大约在同一时间，她开始使用非处方（OTC）非那吡啶片治疗泌尿系统症状。患者缺氧且发绀；然而，动脉血气分析缺乏低氧血症的证据。怀疑存在异常血红蛋白，并通过高铁血红蛋白水平升高得到证实。非那吡啶被认为可能是高铁血红蛋白血症的病因，而患者对此并不知晓。该病例凸显了始终询问非处方药使用情况的重要性，尤其是在老年人群中。
