Random one-hour urine catecholamine and 4-hydroxy-3-methoxymandelic acid assays for diagnosis of pheochromocytoma.

Using randomly voided 1-h urine samples, levels of excretion of catecholamines (CA) and 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid; VMA) were determined in order to save time in and simplify the diagnostic work-up of pheochromocytoma, particularly in out-patient hypertension clinics. Twenty-nine patients with surgically verified pheochromocytoma (15 paroxysmal and 14 sustained type), 56 patients with essential hypertension (26 labile and 30 fixed type) and 14 normal volunteers were studied. Abnormally high excretion of CA and VMA was found in all patients with pheochromocytoma when compared to those with essential hypertension or to normal controls after duly considering the influence of external factors such as food and exercise. From these results, we concluded that assays of CA and VMA even in random 1-h urine samples are useful in separating patients with pheochromocytoma from those with other types of hypertension.