Pheochromocytoma and paraganglioma (PPGL) require prompt consideration and efficient diagnosis and treatment to minimize associated morbidity and mortality. Once considered, appropriate biochemical testing is key to diagnosis. Advances in understanding catecholamine metabolism have clarified why measurements of the O-methylated catecholamine metabolites rather than the catecholamines themselves are important for effective diagnosis. These metabolites, normetanephrine and metanephrine, produced respectively from norepinephrine and epinephrine, can be measured in plasma or urine, with choice according to available methods or presentation of patients. For patients with signs and symptoms of catecholamine excess, either test will invariably establish the diagnosis, whereas the plasma test provides higher sensitivity than urinary metanephrines for patients screened due to an incidentaloma or genetic predisposition, particularly for small tumors or in patients with an asymptomatic presentation. Additional measurements of plasma methoxytyramine can be important for some tumors, such as paragangliomas, and for surveillance of patients at risk of metastatic disease. Avoidance of false-positive test results is best achieved by plasma measurements with appropriate reference intervals and preanalytical precautions, including sampling blood in the fully supine position. Follow-up of positive results, including optimization of preanalytics for repeat tests or whether to proceed directly to anatomic imaging or confirmatory clonidine tests, depends on the test results, which can also suggest likely size, adrenal vs extra-adrenal location, underlying biology, or even metastatic involvement of a suspected tumor. Modern biochemical testing now makes diagnosis of PPGL relatively simple. Integration of artificial intelligence into the process should make it possible to fine-tune these advances.

中文翻译：

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嗜铬细胞瘤和副神经节瘤的生化评估。

嗜铬细胞瘤和副神经节瘤（PPGL）需要及时考虑和有效的诊断和治疗，以尽量减少相关的发病率和死亡率。一旦考虑，适当的生化测试是诊断的关键。了解儿茶酚胺代谢的进展阐明了为什么测量 O-甲基化儿茶酚胺代谢物而不是儿茶酚胺本身对于有效诊断很重要。这些代谢物去甲肾上腺素和变肾上腺素分别由去甲肾上腺素和肾上腺素产生，可以在血浆或尿液中进行测量，根据现有方法或患者的表现进行选择。对于有儿茶酚胺过量体征和症状的患者，任何一项检测都可以确诊，而对于因偶发瘤或遗传倾向而筛查的患者，血浆检测比尿变肾上腺素具有更高的敏感性，特别是对于小肿瘤或无症状的患者。血浆甲氧基酪胺的额外测量对于某些肿瘤（例如副神经节瘤）以及对有转移性疾病风险的患者的监测可能很重要。避免假阳性检测结果的最佳方法是通过适当的参考区间和分析前预防措施进行血浆测量，包括在完全仰卧位进行血液采样。阳性结果的跟进，包括优化重复测试的预分析或是否直接进行解剖成像或验证性可乐定测试，取决于测试结果，这还可以表明可能的大小、肾上腺与肾上腺外的位置、基础生物学、甚至疑似肿瘤的转移。现代生化检测现在使 PPGL 的诊断相对简单。将人工智能集成到流程中应该可以微调这些进步。