Critical Care, Riddle Hospital, Media, Pennsylvania 19063, USA.
Pharmacotherapy. 2012 May;32(5):e98-102. doi: 10.1002/j.1875-9114.2012.01030.x. Epub 2012 Apr 12.
Phenylephrine, an α(1) -adrenergic agonist, and methamphetamine, a prescription drug and substance of abuse, have similar chemical structures and thus have the potential to cross-react in qualitative screening tools such as a urine drug screening (UDS) performed by immunoassay. This cross-reactivity may yield a false-positive result that may affect the provision of care in certain patient populations and clinical situations. We describe a 36-year-old woman with confirmed brain death after a short hospital stay who had an initial UDS that was negative for methamphetamine. The patient was assessed for potential organ donation, which included obtaining a follow-up UDS. A urine sample was obtained after being hospitalized for 36 hours, which tested positive for methamphetamine, with no suspected ingestion of the target substance. Confirmatory laboratory testing indicated that intravenous phenylephrine and its metabolites were the likely cause of the false-positive UDS. However, the patient was not deemed to be a suitable candidate for organ donation, but clear documentation of the reason for denial of organ donation was not available in the patient's medical record. To our knowledge, this is the first case published in the English-language literature that describes the clinical occurrence of apparent immunoassay cross-reactivity of methamphetamine and phenylephrine that resulted in a false-positive UDS for methamphetamine. In addition, this report describes the potential implications of this situation on clinical care, including organ donation acceptance. Toxicology screening in the emergency department and intensive care unit is a tool to assist in the diagnosis of medical conditions, but it may not always be reliable. Therefore, positive immunoassay results that may change the management of a patient's condition should be quickly verified with confirmatory testing to minimize unfavorable consequences.
苯肾上腺素，一种α(1) -肾上腺素能激动剂，和冰毒，一种处方药物和滥用物质，具有相似的化学结构，因此有可能在免疫测定法进行的尿液药物筛选 (UDS) 等定性筛选工具中发生交叉反应。这种交叉反应可能产生假阳性结果，这可能会影响某些患者群体和临床情况下的护理提供。我们描述了一位 36 岁的女性，她在短暂住院后被确诊为脑死亡，最初的 UDS 检测冰毒呈阴性。对该患者进行了潜在器官捐献的评估，包括进行后续 UDS 检测。在住院 36 小时后采集尿液样本，检测结果呈冰毒阳性，且无可疑的目标物质摄入。确认性实验室检测表明，静脉注射苯肾上腺素及其代谢物可能是导致 UDS 假阳性的原因。然而，该患者被认为不适合进行器官捐献，但患者的病历中没有明确记录拒绝器官捐献的原因。据我们所知，这是首次在英文文献中发表的描述苯肾上腺素和冰毒的明显免疫测定交叉反应导致冰毒 UDS 假阳性的临床案例。此外，该报告描述了这种情况对临床护理的潜在影响，包括器官捐献的接受。急诊科和重症监护病房的毒理学筛查是一种辅助诊断医疗状况的工具，但它并不总是可靠的。因此，可能改变患者病情管理的阳性免疫测定结果应尽快通过确证性检测进行验证，以最小化不利后果。
