Cone Edward J, Caplan Yale H, Moser Frank, Robert Tim, Shelby Melinda K, Black David L
Johns Hopkins School of Medicine, Department of Psychiatry and Behavioral Sciences, Baltimore, Maryland 21224, USA.
J Anal Toxicol. 2009 Jan-Feb;33(1):1-7. doi: 10.1093/jat/33.1.1.
Excessive fluid intake can substantially dilute urinary drug concentrations and result in false-negative reports for drug users. Methods for correction ("normalization") of drug/metabolite concentrations in urine have been utilized by anti-doping laboratories, pain monitoring programs, and in environmental monitoring programs to compensate for excessive hydration, but such procedures have not been used routinely in workplace, legal, and treatment settings. We evaluated two drug normalization procedures based on specific gravity and creatinine. These corrections were applied to urine specimens collected from three distinct groups (pain patients, heroin users, and marijuana/ cocaine users). Each group was unique in characteristics, study design, and dosing conditions. The results of the two normalization procedures were highly correlated (r=0.94; range, 0.78-0.99). Increases in percent positives by specific gravity and creatinine normalization were small (0.3% and -1.0%, respectively) for heroin users (normally hydrated subjects), modest (4.2-9.8%) for pain patients (unknown hydration state), and substantial (2- to 38-fold increases) for marijuana/cocaine users (excessively hydrated subjects). Despite some limitations, these normalization procedures provide alternative means of dealing with highly dilute, dilute, and concentrated urine specimens. Drug/metabolite concentration normalization by these procedures is recommended for urine testing programs, especially as a means of coping with dilute specimens.
过量饮水会显著稀释尿液中的药物浓度，导致对吸毒者的检测报告呈假阴性。反兴奋剂实验室、疼痛监测项目以及环境监测项目已采用尿液中药物/代谢物浓度的校正（“归一化”）方法来补偿过度水化的影响，但这些程序在工作场所、法律和治疗环境中尚未常规使用。我们评估了基于比重和肌酐的两种药物归一化程序。这些校正应用于从三个不同组（疼痛患者、海洛因使用者和大麻/可卡因使用者）收集的尿液样本。每个组在特征、研究设计和给药条件方面都各不相同。两种归一化程序的结果高度相关（r = 0.94；范围为0.78 - 0.99）。对于海洛因使用者（正常水化的受试者），通过比重和肌酐归一化后阳性率的增加较小（分别为0.3%和 -1.0%），对于疼痛患者（水化状态未知）适中（4.2 - 9.8%），而对于大麻/可卡因使用者（过度水化的受试者）则显著（增加2至38倍）。尽管存在一些局限性，但这些归一化程序提供了处理高度稀释尿液样本、稀释尿液样本和浓缩尿液样本的替代方法。建议在尿液检测项目中采用这些程序进行药物/代谢物浓度归一化，特别是作为应对稀释样本的一种手段。
