Clinical and neuroendocrinological characteristics of delayed orthostatic hypotension in Parkinson's disease.

Purpose Delayed orthostatic hypotension (DOH), a fall in blood pressure after a 3-min cutoff, is clinically meaningful. The aim of this study was to elucidate the clinical and neuroendocrinological characteristics of DOH in patients with Parkinson's disease (PD). Methods A total of 132 patients with newly diagnosed PD were enrolled. Baseline clinical characteristics, including olfactory function, and changes in norepinephrine (NE) and vasopressin (ADH) concentrations during the head-up tilt test (HUT), were examined. Results Fifty-five patients (42%) had classical orthostatic hypotension (COH), and 19 patients (14%) had DOH. Patients with COH and DOH tended to have more severe hyposmia than patients without OH. A multivariate linear regression model showed that hyposmia was associated with DOH and COH. The increase of heart rate against the fall in blood pressure was significantly lower in patients with COH and DOH than those without OH. The NE levels at supine rest and after upright tilting were lower in the COH group than in the PD without OH and DOH groups. The levels of ADH were higher in the DOH group than in the COH group at supine rest and higher than in the PD without OH group after upright tilting. There was no significant difference in the cardiac 123I-MIBG scintigraphy between the COH and DOH groups. Conclusion Compared with patients without OH, patients with DOH had severe hyposmia. Relatively preserved peripheral sympathetic nervous system function in patients with DOH suggests that DOH might be an early and milder form of OH in PD.