Maximum Flow Rate is Lowest in the Early Morning in Hospitalized Men With Nocturia Evaluated Over 24 Hours by Toilet Uroflowmetry

Abstract

ObjectivesTo investigate urination parameters measured by toilet uroflowmetry in hospitalized men with nocturia over a 24-hour period to clarify the circadian rhythm of urination. Physicians often encounter male patients with complaints of low maximum flow rate only in the early morning. However, this has not been proved scientifically because most urinary examinations are generally performed for outpatients only during the daytime. MethodsThis retrospective study included 117 hospitalized male patients (age, 68.7 ± 12.8 years). The data of 4689 urinations during their hospital stay were evaluated on the ward by toilet uroflowmetry, which is a toilet-type device that allows patients to urinate as usual. The records including voided volume, maximum flow rate, and voiding time were evaluated as averages of 8 time periods of 3 hours each by generalized linear mixed models with an identity link function to adjust for personal bias. ResultsVoided volume after adjustment for age was significantly higher during the nighttime (21:00-06:00) than that in the morning (06:00-09:00) and highest from 00:00-03:00. Interestingly, even after adjustment for both voided volume and age, the maximum flow rate from 06:00-09:00 was the lowest. Voiding time after adjustment for age and voided volume was significantly higher during the nighttime (00:00-06:00) than that from 06:00-09:00. ConclusionWe clearly showed the circadian rhythm of urination in a group of hospitalized men with nocturia. Maximum flow rate was lowest in the early morning, including just after waking up.