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.