Single-voided urine metanephrine assays in screening for pheochromocytoma

To facilitate the screening for pheochromocytoma, we have validated the use of single-voided, spot urine specimens for the determination of total metanephrines. Metanephrine excretion was found to be quite constant throughout the day and night in ten patients with essential hypertension and seven patients with pheochromocytoma. The levels in single-voided specimens were closely correlated to those in 24-hour specimens in 100 hypertensive subjects. The mean +/- 2 SD metanephrine excretion in single-voided urine specimens from 500 hypertensive subjects was 0.351 +/- 0.356 mug/mg of creatinine.