Abstract
BACKGROUND: Nocturia is the most common lower urinary tract symptom (LUTS) in Parkinson's disease (PD) and impacts sleep and subsequent daytime function. Often nocturia in PD is attributed to overactive bladder, however we explored the contribution of the over-production of urine at night, nocturnal polyuria (NP), as another factor. OBJECTIVES: To assess the prevalence and severity of NP in a PD cohort with LUTS and explore associations with autonomic and other patient characteristics. METHODS: Sub-study nested within a trial for LUTS in PD. All participants performed 72-hour bladder diaries. Nocturnal polyuria index (NPi) was calculated from diaries and key associations were explored. RESULTS: 62.6 % of participants had NP based on the NPi33 threshold (producing > 33 % urine at night). Increasing NPi was strongly significantly associated with greater nocturia (OR 1.7 per 5 % NPi unit; 1.5-2.0; P < 0.001). A significant association was observed between NPi and orthostatic hypotension (OR 1.2 per 5 % NPi unit increase; 1.0-1.4; P = 0.03) and reported cardiovascular symptoms (coefficient 0.07; 0.03-0.11; P = 0.002). A marked association was seen with severe NP and orthostatic hypotension (OR 4.9; 1.56-15.57; P = 0.006). CONCLUSION: NP is very common in this PD cohort symptomatic for LUTS, and is closely associated with increasing rate of nocturia. NP is linked to cardiovascular symptoms and autonomic dysfunction, particularly blood pressure lability which may be causal or simply reflect advanced disease state.