Postprandial and orthostatic hypotension in Parkinson's disease.

In this study, the 24-hour pattern of blood pressure (BP), heart rate, and urinary catecholamine (CA) excretion and the response of BP and plasma CA to the tilt test have been investigated in 13 untreated patients affected by Parkinson's disease (PD) and in 11 age-matched healthy controls. Seven of the 13 PD subjects showed a fall of supine systolic BP greater than that in controls (ie, exceeding 20\% of the preprandial value). A significant relationship was found in the PD group between the degree of postprandial hypotension and the 24-hour mean value of dopamine excretion. Eight PD subjects also showed orthostatic hypotension during the tilt test (performed in the morning hours) and in the postprandial phase. Basal norepinephrine plasma levels of PD patients, as well as their percentage increases on standing, were within the range of the controls. These data suggest the existence of a subtype of PD patient, characterized by a widespread impairment of cardiovascular responsiveness and bordering on syndromes of autonomic failure such as progressive autonomic failure or multiple system atrophy, or both