Pheochromocytoma, vanillylmandelic acid

The study of urinary vanillylmandelic acid is of considerable importance for the detection of pheochromocytoma, as will be pointed out later. 

Pheochromocytoma can best be detected by studying the urinary elimination of vanillylmandelic acid. Armstrong et al. (A16) first demonstrated that the elimination of this metabolite of epinephrine and norepinephrine is greatly increased in such patients. The amount found in urine ranges, generally, from 10 to 100 times that of epinephrine and norepinephrine (G13), so that the study of the increase in urinary vanillylmandelic acid appears to be a better way of detecting pheochromocytoma than the study of the increase in the catecholamines themselves. Furthermore, an abnormal elimination of vanillylmandelic acid together with a normal excretion of catecholamines can occur in patients with pheochromocytoma in the normotensive state (K12) this fact shows the superiority of the vanillylmandelic acid determination upon the determination of catecholamines for the detection of these tumors. 

The urinary elimination of vanillylmandelic acid returns to normal levels in patients with pheochromocytoma following excision of the tumor it is normal in hypertensive patients other than cases of pheochromocytoma (S41). 

Various techniques, which are rather time consuming for routine use, have been described for the quantitative determination of vanillylmandelic acid in urine (G12). Rapid and more simple techniques, however, allow the semiquantitative estimation of that acid and are especially useful for screening hypertensive subjects for the presence of a pheochromocytoma. Among these rapid techniques, the one which was recently described by Gitlow and Kruk (Gll) allows the use of random urine specimens, whereas the previous ones required that the patient avoid certain foods and drugs prior to the sample collection. 

In patients suspected of having a neoplasm of the adrenal medulla that is secreting excessive quantities of epinephrine or norepinephrine (a pheochromocytoma), either the catecholamines themselves (epinephrine, norepinephrine, and dopamine) or their metabolites (the metanephrines and vanillylmandelic acid, VMA) may be measured in a 24-hour urine collection, or the level of catecholamines in the blood may be measured. A patient who has consistently elevated levels in the blood or urine should be considered to have a pheochromocytoma, particularly if the patient has signs and symptoms of catecholamine excess, such as excessive sweating, palpitations, tremulousness, and hypertension. 

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