A Five-Year Report on Experience in the Detection of Pheochromocytoma

Objective: The purpose of the study is to identify biochemical tests that are good predictors for the diagnosis of pheochromocytoma in patients at hypertension. Setting: Review of data from of 3826 patients studied over a 5-year period, between 1994 and 1998, at the University Hospital “Virgen de la Arrixaca” Murcia, Spain. Design and Methods: A retrospective study for the diagnosis of pheochromocytoma of 24-h urinary free catecholamines (norepinephrine, epinephrine, and dopamine) measured by high-performance liquid chromatography (HPLC)-electrochemical detector (ECD), total metanephrines (MNt), and vanillylmandelic acid measured by spectrophotometric methods. Results: During this period, 57 patients were found to have pheochromocytoma, being 47 sporadic, 9 with multiple endocrine neoplasia type 2A, and 1 with neurofibromatosis. In all patients multiple endocrine neoplasia type 2A the tumor were bilateral but only in four of the sporadic tumor group (p< 0.0001, Fisher’s exact test). MNt was determined to be the best discriminator of hypertension and pheochromocytoma. It scored a sensitivity of 94.7% (95% confidence interval, 88.3–99.9%), a specificity of 95.3% (89.5–99.9%), and thus had the best negative predictive value of 99.9% (99.8–99.9%), and this biochemical test also had the best positive predictive value of 23.3% (10.8–59.9%). When combining both MNt and norephinephrine, the positive predictive value to increases to 85.6% (65.3–95.6%). Conclusion: Urinary 24-h MNt excretion level is the best single biochemical test for screening and, in combination with norephinephrine, is diagnostic of the presence of pheochromocytoma.