Pathophysiological aspects of nocturia in a Danish population of men and women age 60 to 80 years

Purpose: We applied the International Continence Society Guidelines and categorized men and women with nocturia 2 or more times a night in pathophysiological groups based on selected lower urinary tract symptoms, clinical examination, frequency volume charts and urodynamics, and categorized the most likely pathophysiological causes of nocturia. Materials and Methods: Participants were randomly selected among respondents in a population study of 4,000 individuals 60 to 80 years old living in Copenhagen County. Nocturia was assessed using the new and validated Nocturia, Nocturnal Enuresis, and Sleep-interruption Questionnaire. Nocturic (2 or more voids) or control (less than 1 void) status was assessed by a 3-day frequency volume chart. Participants were interviewed regarding lower urinary tract symptoms, and physical examination was performed. Nocturia pathophysiology was divided in 4 groups according to frequency volume chart variables, that is nocturnal polyuria, low bladder capacity, nocturnal polyuria and low bladder capacity in combination, and polyuria. Spontaneous flow rate and post-void residual urine were determined, and invasive urodynamic examination was performed in patients. Results: Of 1,111 eligible individuals 75 patients and 75 controls were included. More patients vs controls had daytime frequency, urgency and urge incontinence. However, the difference was not significant in men. Nocturnal polyuria was the only pathophysiological finding that differed significantly in prevalence between patients and controls. The most prevalent urodynamic finding in patients was detrusor overactivity incontinence (26%) in women and detrusor overactivity (64%) in men. Conclusions: Urgency in women, and symptoms suggestive of bladder outlet obstruction in men were the major complaints. Frequency volume charts demonstrated that 55% of patients had nocturnal polyuria which was significantly more than controls. From frequency volume chart variables alone we could categorize 84% of the patients. When symptoms and urodynamic examination were added to the assessment, the most likely cause of nocturia was categorized in 96% of participants.