Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada.
Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.
Cancer Epidemiol Biomarkers Prev. 2018 Aug;27(8):882-891. doi: 10.1158/1055-9965.EPI-18-0018. Epub 2018 May 31.
Total nicotine equivalents (TNE), the sum of nicotine and metabolites in urine, is a valuable tool for evaluating nicotine exposure. Most methods for measuring TNE involve two-step enzymatic hydrolysis for indirect quantification of glucuronide metabolites. Here, we describe a rapid, low-cost direct LC/MS assay. In 139 smokers' urine samples, Bland-Altman, correlation, and regression analyses were used to investigate differences in quantification of nicotine and metabolites, TNE, and nicotine metabolite ratio (NMR) between direct and indirect LC/MS methods. DNA from a subset ( = 97 smokers) was genotyped for and , and the known impact of these variants was evaluated using urinary ratios determined by the direct versus indirect method. The direct method showed high accuracy (0%-9% bias) and precision (3%-14% coefficient of variation) with similar distribution of nicotine metabolites to literary estimates and good agreement between the direct and indirect methods for nicotine, cotinine, and 3-hydroxycotinine (ratios 0.99-1.07), but less agreement for their respective glucuronides (ratios 1.16-4.17). The direct method identified urinary 3HC+3HC-GLUC/COT as having the highest concordance with plasma NMR and provided substantially better estimations of the established genetic impact of glucuronidation variants compared with the indirect method. Direct quantification of nicotine and metabolites is less time-consuming and less costly, and provides accurate estimates of nicotine intake, metabolism rate, and the impact of genetic variation in smokers. Lower cost and maintenance combined with high accuracy and reproducibility make the direct method ideal for smoking biomarker, NMR, and pharmacogenomics studies. .
总尼古丁当量（TNE）是尿液中尼古丁和代谢物的总和，是评估尼古丁暴露的有用工具。大多数测量 TNE 的方法都涉及两步酶水解，以间接定量葡萄糖醛酸代谢物。在这里，我们描述了一种快速、低成本的直接 LC/MS 测定法。在 139 名吸烟者的尿液样本中，采用 Bland-Altman、相关和回归分析来研究直接和间接 LC/MS 方法在尼古丁和代谢物、TNE 和尼古丁代谢物比（NMR）定量方面的差异。从亚组（=97 名吸烟者）的 DNA 中进行了 和 的基因分型，并使用直接与间接方法确定的尿比值评估了这些变体的已知影响。直接法显示出较高的准确性（0%-9%的偏差）和精密度（3%-14%的变异系数），与文献估计的尼古丁代谢物分布相似，并且直接法与间接法在尼古丁、可替宁和 3-羟基可替宁（比值 0.99-1.07）方面具有良好的一致性，但各自葡萄糖醛酸苷的一致性较差（比值 1.16-4.17）。直接法确定尿液 3HC+3HC-GLUC/COT 与血浆 NMR 具有最高的一致性，并与间接法相比，为葡萄糖醛酸苷变体的遗传影响提供了更准确的估计。直接定量尼古丁和代谢物的方法耗时更少，成本更低，并且可以准确估计吸烟者的尼古丁摄入量、代谢率和遗传变异的影响。较低的成本和维护成本与高精度和重现性相结合，使直接法成为吸烟生物标志物、NMR 和药物基因组学研究的理想方法。
