Fluctuation of night time frequency in patients with symptomatic nocturia

BACKGROUND: We examined the fluctuation and causes of voiding frequency during the night in patients with symptomatic nocturia. MATERIALS AND METHODS: Actual night time frequency was recorded by 72 patients for a total of 769 nights (mean 10.7 nights per patient) and was compared with the 'nocturia score' of the International Prostate Symptom Scores (I-PSS). If a patient experienced nocturnal frequency higher or lower than usual, he or she checked the items on a questionnaire considered reasons for the changes. RESULTS: For 471 nights of 769 (61%), actual voiding frequency did not correspond with nocturia score. Patient-by-patient fluctuation in actual voiding frequency during the night was marked. The most prevalent patient-reported reason for fluctuation was amount of fluid intake, followed by duration of time in bed, feeling colder or warmer during time in bed and increased difficulty going to sleep. Fatigue, difficulty going to sleep and salt intake could affect night time frequency positively or negatively. When nocturia score and total score of the I-PSS were high, the differences between actual nocturnal frequency and nocturia score were significantly larger (3 or less, 0.71; 3-4 or more, 1.05, P<0.0001 and 13 or less, 0.78; 14 or more, 0.97; P=0.0030, respectively). Female patients tended to have nocturia scores differing from actual frequency of urination (1.03 versus male patients 0.84, P=0.0673). CONCLUSIONS: There is considerable discrepancy between the nocturia score of the I-PSS and actual voiding frequency, in addition to marked fluctuation of actual voiding frequency in symptomatic patients. Patient perception of fluctuation of night time frequency can provide clues to useful clinical education of patients regarding nocturia.