Noradrenaline Release and Metabolism in Orthostatic (Postural) Hypotension

Fifteen hypotensive patients were studied of whom only seven could be classified as having idiopathic orthostatic (postural) hypotension. These seven patients showed a marked decrease in their urinary output of the sympathetic neurohormone, noradrenaline. Furthermore, the rate of metabolism of circulating noradrenaline was somewhat less than normal; however, there was no significant alteration in noradrenaline metabolites. One patient, on whom autopsy was performed, showed degeneration of the sympathetic ganglia and nerves. Although there was infiltration with amyloid in these areas, it was not certain that amyloidosis was the primary disease. Nevertheless, there was an anatomic loss of the neurogenic structures involved in the synthesis of noradrenaline, which could explain the subnormal output of noradrenaline. Whereas, these results do not permit a definite conclusion that in idiopathic orthostatic hypotension there is an anatomic deficit or a decrease in efferent sympathetic neurons, nevertheless, evidence is presented which would seem to indicate this as the probable etiology.