Classification and distribution of symptomatic nocturia with special attention to duration of time in bed: a...

To classify the night-time urinary frequency of patients with symptomatic nocturia by urine volume produced, nocturnal bladder capacity and time spent in bed.

In all, 110 patients whose principal complaint was nocturia were enrolled in the study; 32 age- and gender-matched subjects were recruited as controls. From studies of the controls, 190 mL and 510 min were identified as the normal limits for mean nocturnal urine voided volume and time spent in bed. The 110 patients were classified into eight categories based on urine volume, nocturnal bladder capacity and time spent in bed.

There were abnormalities of urine volume produced, bladder capacity and time spent in bed in 72%, 50% and 54% of the patients, respectively. Patients with severe nocturia (> or =4 voids/night) tended to have more complex pathophysiology than those with mild nocturia (< or =3 voids/night).

Time spent in bed, urine volume produced and bladder capacity should be used to assess patients with symptomatic nocturia.