Autonomic hyperreflexia and its differentiation from pheochromocytoma.

Conceivably pheochromocytoma may have to be differentiated from autonomic hyperreflexia as the cause of paroxysmal hypertension. Elevated urinary catecholamine metabolites may occur in both conditions. However, marked elevations of serum dopamine-beta-hydroxylase (DBH) accompanied by relatively slight elevations of plasma catecholamines are observed during hypertensive paroxysms in patients with autonomic hyperreflexia, while marked elevations of plasma catecholamines with little if any change in serum DBH concentration are characteristic of hypertensive paroxysms caused by pheochromocytoma.