Plasma or Urinary Metanephrines for the Diagnosis of Pheochromocytoma? That Is the Question

Several clinical disorders mimic the signs and symptoms of pheochromocytoma; the definitive diagnosis of this condition thus rests primarily on showing excessive and inappropriate production of catecholamine. Because pheochromocytoma is fatal if undiagnosed, biochemical tests used to detect it should have a high sensitivity. In addition, the predictive value of any negative test result should exclude false-negative results as efficiently as possible. A false-positive result is relatively less important because additional testing (using, for example, clonidine suppression, glucagon stimulation, and imaging techniques) can be done to rule out the disease.

In an article recently published in Annals [1], Lenders and colleagues reported that tests for measuring plasma metanephrine levels are more sensitive than tests for measuring plasma catecholamine levels and 24-hour urinary metanephrine levels (sensitivities of 100%, 85%, and 89%, respectively). In this study, the negative predictive value of …