In this study, the concentration of urinary creatinine (Cr) and urine color were analyzed, and a correlation obtained, to objectively verify normal urine samples prior to forensic drug testing. Cr was analyzed via a colorimetric method based on the Jaffé reaction using a Cobas C-311 analyzer (Roche SA, Basel, Switzerland; Hitachi, Tokyo, Japan). The Cr concentration for urine specimen validity testing was measured to screen urine samples submitted after dilution or upon the addition of a foreign substance that interferes with drug testing. Urine samples containing < 20 mg/dL of Cr were classified as abnormal. The Korea Standard Color Analysis program was used for urine color analysis and correlations with Cr concentration analyzed. The color and Cr concentration of 271 urine samples were analyzed according to age and sex. The mean ± standard deviation of Cr concentration in males and females was 136.4 ± 66.2 mg/dL and 109.5 ± 71.1 mg/dL, respectively, with a statistically insignificant difference (p = 0.4554). Furthermore, the participants were categorized into young (19–34 years), middle-aged (35–49 years), and elderly (≥ 50 years) groups to compare Cr concentration; however, no significant difference was found (p = 0.2143–0.983). Strong variable correlations were identified between Cr and the characteristics of urine color. Despite various factors such as water consumption, health problems, and vitamins, urine color was found applicable for urine specimen validity testing. Future plans include the development of a smartphone camera application for use in urine color analysis to identify abnormal urine samples.

中文翻译：

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尿肌酐浓度和尿液颜色作为样本有效性测试的指标

在这项研究中，分析了尿肌酐（Cr）浓度和尿液颜色，并获得了相关性，以便在法医药物检测之前客观地验证正常尿液样本。使用 Cobas C-311 分析仪（Roche SA，巴塞尔，瑞士；日立，东京，日本）通过基于 Jaffé 反应的比色法对 Cr 进行分析。测量尿液样本有效性测试的 Cr 浓度，以筛选稀释后或添加干扰药物测试的异物后提交的尿液样本。含有 < 20 mg/dL Cr 的尿液样本被归类为异常。使用韩国标准颜色分析程序进行尿液颜色分析并分析与 Cr 浓度的相关性。根据年龄和性别对 271 份尿液样本的颜色和 Cr 浓度进行了分析。男性和女性 Cr 浓度的平均值±标准差分别为 136.4 ± 66.2 mg/dL 和 109.5 ± 71.1 mg/dL，差异无统计学意义（p = 0.4554）。此外，将参与者分为青年组（19-34岁）、中年组（35-49岁）和老年组（≥50岁）来比较Cr浓度；然而，没有发现显着差异（p = 0.2143–0.983）。Cr 和尿液颜色特征之间存在很强的变量相关性。尽管存在饮水量、健康问题和维生素等多种因素，但尿液颜色仍适用于尿液样本有效性测试。未来的计划包括开发智能手机摄像头应用程序，用于尿液颜色分析，以识别异常尿液样本。