Kim James A, Ptolemy Adam S, Melanson Stacy E F, Janfaza David R, Ross Edgar L
Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Pain Med. 2015 Jun;16(6):1073-6. doi: 10.1111/pme.12265. Epub 2013 Oct 18.
The urine of a patient admitted for chest and epigastric pain tested positive for cocaine using an immunoassay-based drug screening method (positive/negative cutoff concentration 150 ng/mL). Despite the patient's denial of recent cocaine use, this positive cocaine screening result in conjunction with a remote history of drug misuse impacted the patient's recommended pain therapy. Specifically, these factors prompted the clinical team to question the appropriateness of opioids and other potentially addictive therapeutics during the treatment of cancer pain from previously undetected advanced pancreatic carcinoma.
After pain management and clinical pathology consultation, it was decided that the positive cocaine screening result should be confirmed by gas chromatography-mass spectrometry (GC-MS) testing.
This more sensitive and specific analytical technique revealed that both cocaine and its primary metabolite benzoylecgonine were undetectable (i.e., less than the assay detection limit of 50 ng/mL), thus indicating that the positive urine screening result was falsely positive. With this confirmation, the pain management service team was reassured in offering intrathecal pump (ITP) therapy for pain control. ITP implantation was well tolerated, and the patient eventually achieved excellent pain relief. However, ITP therapy most likely would not have been utilized without the GC-MS confirmation testing unless alternative options failed and extensive vigilant monitoring was initiated.
As exemplified in this case, confirmatory drug testing should be performed on specimens with unexpected immunoassay-based drug screening results. To our knowledge, this is the first report of a false-positive urine cocaine screening result and its impact on patient management.
一名因胸痛和上腹部疼痛入院的患者，使用基于免疫分析的药物筛查方法检测尿液中可卡因呈阳性（阳性/阴性临界浓度为150 ng/mL）。尽管患者否认近期使用过可卡因，但这一可卡因筛查阳性结果以及既往药物滥用史影响了对该患者推荐的疼痛治疗方案。具体而言，这些因素促使临床团队质疑在治疗先前未被发现的晚期胰腺癌引起的癌痛时使用阿片类药物和其他潜在成瘾性治疗方法的适宜性。
在进行疼痛管理和临床病理会诊后，决定通过气相色谱-质谱联用（GC-MS）检测来确认可卡因筛查阳性结果。
这种更灵敏、特异的分析技术显示，可卡因及其主要代谢物苯甲酰爱康宁均未被检测到（即低于50 ng/mL的检测限），这表明尿液筛查阳性结果为假阳性。有了这一确认结果，疼痛管理服务团队放心地为患者提供鞘内泵（ITP）治疗以控制疼痛。ITP植入耐受性良好，患者最终实现了极佳的疼痛缓解。然而，如果没有GC-MS确认检测，除非其他替代方案无效并开始进行广泛的密切监测，否则很可能不会采用ITP治疗。
如本病例所示，对于基于免疫分析的药物筛查结果意外的标本，应进行确证性药物检测。据我们所知，这是关于尿液可卡因筛查假阳性结果及其对患者管理影响的首例报告。
