Catecholamine determination in sequential urine voiding: a method for detecting pheochromocytoma in patients without elevated urinary catecholamines.

The biochemical diagnosis of pheochromocytoma is based on the demonstration of increased amounts of catecholamines, or catecholamine metabolites, in 24-h urine samples. In patients whose 24-h urine catecholamines are within normal limits, and in whom short duration catecholamine elevations are suspected, timed urine collections have been used to detect these elevations. In this study, determination of catecholamines in sequential urine voidings and consideration of their relative values are suggested as a further method to detect pheochromocytomas, especially in cases without extended elevation of urinary catecholamine levels. The use of this method is demonstrated in three cases in which pheochromocytoma would not otherwise have been proven by laboratory determination.