Background: Screening tests for pheochromocytoma involve measuring levels of catecholamines in the urine or plasma, which have significant false-positive rates. We reviewed patients with adrenal masses and elevated levels of catecholamines to determine the value of different preoperative tests in diagnosing pheochromocytomas.
Methods: A retrospective chart review identified patients who underwent adrenalectomy between 1997 and 2011 with elevation of urine or serum catecholamines. A database of clinicopathologic factors was created including preoperative urine and plasma metanephrines, normetanephrines, vanillylmandelic acid, and fractionated catecholamines, and tumor dimensions on imaging and pathology.
Results: A total of 70 patients underwent adrenalectomy because of presence of an adrenal mass and elevation of catecholamines or normetanephrines or metanephrines. Of these, 46 had pathologically confirmed pheochromocytomas. To improve our ability to discriminate between pheochromocytoma and other pathology, we examined different combinations of clinicopathologic factors and catecholamine levels and found the best test was a scoring system. Points are awarded for a hierarchy of elevated normetanephrine, norepinephrine, metanephrines, with additional points received for age <50 and size on imaging >3.3 cm. A score of 2 is suggestive of pheochromocytoma, with a positive predictive value of 86-87%, while a score of 4 is diagnostic with positive predictive value of 100%.
Conclusion: We found that urine/serum normetanephrine levels were the most valuable screening tool; however, a score examining the size of adrenal mass on preoperative CT, age, and either plasma or urine norepinephrine, metanephrine, and normetanephrine values leads to a higher positive predictive value, making this scoring system superior to individual lab tests.