Circadian Rhythm of Voided Volume, Maximum Flow Rate, and Voiding Time Evaluated by Toilet Uroflowmetry in Hospitalized Women With Nocturia.

OBJECTIVE:To clarify the circadian rhythm of urination in hospitalized women with nocturia measured by toilet uroflowmetry and its age-related change. METHODS:We evaluated 2602 urinations of 58 female patients (age, 68.4 ± 15.2 years) who were hospitalized in our institution for urological disease. We assessed voided volume (VV) as averages of every hour by generalized linear mixed models with an identity link function to adjust for personal bias and age. Maximum flow rate and voiding time were analyzed by the same method after adjustment for age, personal bias, and VV. We also compared these circadian rhythms between women <70 and ≥70 years. RESULTS:VVs in the nighttime were significantly higher than that from 06:00-07:00 (205.6 ± 11.7 ml). Maximum flow rates in the afternoon were significantly higher than that from 06:00-07:00 (18.8 ± 0.93 ml/sec). Voiding time showed no statistically significant difference between the values at any time of day and that from 06:00-07:00. We also showed that the circadian rhythm of VV becomes less clear in the elderly women (P interaction = .0057). However, no significant difference was found in the maximum flow rate and voiding time regarding the pattern of the circadian rhythm between women <70 and ≥70 years old. CONCLUSION:The present study clearly showed a circadian rhythm of VV and maximum flow rate in hospitalized women with nocturia. In addition, the pattern of the circadian rhythm of VV was attenuated in women ≥70 years old.