VMA excretion in patients with pheochromocytoma.

Studies in 20 patients, and a reanalysis of previously published data demonstrate that there is a significant linear relationship between the rate of urinary excretion of 3-methoxy-4-hydroxymandelic acid and the size of a pheochromocytoma. This relationship is most significantly demonstrated in a small group of patients with bilateral adrenal disease as part of the MEN II syndrome. Since not all pheochromocytomas are accurately localized preoperatively and significant numbers can be bilateral or extra-adrenal, this predictive index of tumor size has useful surgical implications. An obvious discrepancy between a prediction of size and operative findings should alert the surgeon to a more thorough search of the opposite adrenal and, indeed, all extra-adrenal paraganglionic sites for other secreting tumor tissue.