Yu R, Wei M
Division of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
Exp Clin Endocrinol Diabetes. 2010 Oct;118(9):577-85. doi: 10.1055/s-0029-1237699. Epub 2009 Dec 8.
Testing for pheochromocytoma becomes more frequent in clinical practice. False positive test results may cause patient anxiety and unnecessary imaging studies. The data on false positive results for pheochromocytoma in routine clinical practice are lacking. To examine the prevalence of false positive results and to reveal the clinical features and laboratory tests of patients with markedly elevated but false positive test results, a database of tests for pheochromocytoma at a large general hospital between 2000 and 2008 was reviewed. Of 1,896 patients tested, 417 (22.0%) had at least one abnormal test result and 66 (3.5%) had markedly elevated results. 24 patients with markedly elevated but false positive results received 65 imaging studies and 1 adrenalectomy. The causes of the misleading results included physiological variations (33%), laboratory errors (29%), and drug interference with measurement (21%). The false positive rate of a markedly elevated result was lowest for vanillylmandelic acid (9%) and highest for urine metanephrines (50%) (p = 0.03). Nearly half of all test results were normal and 79% of patients had at least one normal result. Therefore false positive test results for pheochromocytoma are rather common. Markedly elevated but false positive test results can potentially be avoided by judicious selection of patients and tests. Pretest risk, physiological variations of catecholamine levels, laboratory errors, and drug interference should be considered in interpreting abnormal test results.
在临床实践中，嗜铬细胞瘤的检测变得更加频繁。假阳性检测结果可能会导致患者焦虑以及不必要的影像学检查。目前缺乏关于常规临床实践中嗜铬细胞瘤假阳性结果的数据。为了检查假阳性结果的发生率，并揭示检测结果显著升高但为假阳性的患者的临床特征和实验室检查情况，我们回顾了一家大型综合医院在2000年至2008年间的嗜铬细胞瘤检测数据库。在1896名接受检测的患者中，417名（22.0%）至少有一项检测结果异常，66名（3.5%）检测结果显著升高。24名检测结果显著升高但为假阳性的患者接受了65次影像学检查和1次肾上腺切除术。导致结果误导的原因包括生理变异（33%）、实验室误差（29%）以及药物对测量的干扰（21%）。香草扁桃酸检测结果显著升高时的假阳性率最低（9%），尿甲氧基肾上腺素的假阳性率最高（50%）（p = 0.03）。几乎所有检测结果的一半是正常的，79%的患者至少有一项正常结果。因此，嗜铬细胞瘤的假阳性检测结果相当常见。通过明智地选择患者和检测方法，有可能避免检测结果显著升高但为假阳性的情况。在解释异常检测结果时，应考虑检测前风险、儿茶酚胺水平的生理变异、实验室误差和药物干扰。
