Abstract
<title>Abstract</title> <p>Purpose To compare serum chromogranin A, norepinephrine, and orexin A concentrations in patients with Parkinson disease with and without orthostatic hypotension and to examine their associations with autonomic and sleep-related measures. Methods This single-center cross-sectional study included 118 patients with Parkinson disease, of whom 63 had orthostatic hypotension and 55 did not. Blood pressure was measured after supine rest and at one and three minutes after standing. Motor severity, disease stage, non-motor symptoms, autonomic symptoms, nocturnal sleep problems, and daytime sleepiness were assessed using validated clinical scales. Serum biomarkers were measured by enzyme-linked immunosorbent assay. Group comparisons, correlation analyses, and exploratory receiver operating characteristic analyses were performed. Results Chromogranin A concentrations were lower in the orthostatic hypotension group than in the group without orthostatic hypotension (1436 ± 322 versus 1907 ± 971 nanograms per liter; p = 0.034), as were orexin A concentrations (402 ± 115 versus 544 ± 410 nanograms per liter; p = 0.030). Norepinephrine concentrations did not differ significantly. Motor examination, autonomic symptom, and Hoehn and Yahr stage scores were higher in the orthostatic hypotension group. Orexin A was not associated with subjective sleep measures but showed weak inverse associations with autonomic symptom and motor examination scores. All evaluated markers had limited discrimination for orthostatic hypotension. Conclusion Lower serum chromogranin A and orexin A were associated with orthostatic hypotension in Parkinson disease, whereas resting norepinephrine was not. These biomarkers remain investigational and should not replace standardized orthostatic blood pressure testing.</p>