OBJECTIVE Pheochromocytoma/Paraganglioma (PPGL) is a rare tumor with non-specific presentations overlapping common entities like anxiety, hypertension, acute illness and episodic "spells." Assessment of urine normetanephrine or metanephrine (UNM-UMN) in real-life, where PPGL is very rare and PPGL mimics extremely common, may show overlap in results with loss of specificity depending on the reference range. We determined the extent to which UNM-UMN are high in people undergoing screening for PPGL. DESIGN AND METHODS Retrospective review of all UNM-UMN performed in a central lab serving Southern Alberta over 8 years. RESULTS After excluding pediatric ages and patients with CKD, there were 12,572 unique patients with 14,383 measures of UNM-UMN. 85 patients (0.7%) had markedly high UNM-UMN compatible with likely PPGL. Depending on the age category (in decades), 10-22% of all UNM results were above the upper reference limit(URL), particularly between ages of 40-60. Less than 3% had elevations in both UNM and UMN. Of those with high UNM, 99% were less than 3-fold the URL. Based on the population data, a potential new reference range for UNM is suggested, which may be more appropriate to the types of patient who undergo this form of testing. CONCLUSIONS There is an extraordinarily high prevalence of high UNM seen in real-life use of the test. However, the vast majority of high UNM are unlikely to be PPGL given the disease rarity and the massive number of tests ordered. This suggests the current laboratory URL may be too low (poor specificity) and/or the reference range may not be appropriate to the type of patient being screened for PPGL. Depending on the frequency of use of any screening test in a population, if the disease is rare and the specificity of the test is poor, a high rate of false positive results will be expected.

中文翻译：

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在大的，未分化的人群中筛查嗜铬细胞瘤时，假阳性生化结果的发生率很高，且检测的适应症可变。

目的嗜铬细胞瘤/淋巴神经胶质瘤（PPGL）是一种罕见的肿瘤，具有非特异性表现，覆盖了常见的实体，如焦虑症，高血压，急性疾病和发作性“咒语”。在现实生活中评估尿液中的去甲肾上腺素或间肾上腺素（UNM-UMN）可能会导致结果重叠，但特异性降低，具体取决于参考范围，在这种情况下，PPGL极为罕见，而PPGL的模拟极为罕见。我们确定了UNM-UMN在接受PPGL筛查的人群中所占的比例。设计与方法回顾性回顾了在为南艾伯塔省提供服务的中心实验室中进行了8年的所有UNM-UMN的情况。结果排除儿科年龄和CKD患者后，共有12572名独特患者接受了14383项UNM-UMN量度。85例患者（0.7％）的UNM-UMN与可能的PPGL显着较高。根据年龄类别（数十年），UNM所有结果中有10-22％高于参考上限（URL），尤其是在40-60岁之间。联厄特派团和UMN的海拔都低于3％。在UNM高的用户中，有99％的用户的URL不到3倍。根据人群数据，建议UNM的潜在新参考范围，这可能更适合接受这种形式的测试的患者类型。结论在现实生活中使用该测试时，高UNM患病率异常高。但是，鉴于这种疾病的稀有性和订购的大量检测手段，绝大多数高UNM患者不太可能是PPGL。这表明当前实验室URL可能太低（特异性差）和/或参考范围可能不适合针对PPGL筛查的患者类型。