Variability of 24-hour voiding diary variables among asymptomatic women

We determine whether urinary diary values are stable over time among women without lower urinary tract symptoms.

Women without lower urinary tract symptoms completed a 24-hour log of fluid intake and volumes voided during June/July 2001 and again during February/March 2002. Initial and repeat diaries were compared using Wilcoxin signed rank tests, considered significant at the 5% level.

A total of 137 subjects completed both diaries. Subjects voided a median of 8 times per 24 hours during the first and 7 per 24 hours during the second diary with 95% of subjects recording fewer than 13 voids per 24 hours during both diaries. Nighttime voids were recorded by 59 (43%) subjects during the first and 54 (39%) during the second diary. Urinary frequency and total urine volume were significantly greater during the first than second diary (Z = 2.1, p = 0.03 and Z = 3.3, p = 0.001, respectively). No significant differences in mean voided volume, maximum voided volume, voids per liter intake, total intake, or daytime or nighttime diuresis rates were found when the groups were compared. However, there were large individual differences in all diary variables.

While there is large individual variation in diary values, pooled data from 24-hour urinary diaries concerning voids per liter intake, and mean and maximum voided volumes remain stable. Pooled data concerning raw urinary frequency and urine volumes may vary significantly without any treatment. When urinary frequency is of interest, the number of voids per liter intake may represent the most stable measure.