Urinary habits among asymptomatic women

Objective: The purpose of this study was to determine normal ranges for voiding diary variables for a racially diverse sample of women without lower urinary tract symptoms in the United States. Study Design: Three hundred women without lower urinary tract symptoms completed a 24-hour log of fluid intake and volumes voided. We used linear regression to analyze diary data according to patient characteristics, which included race, age, body mass index, and parity. Results: The following races were represented: black, 118 women (39%); white, 117 women (39%); Hispanic, 36 women (12%); Asian, 28 women (9%); and mixed race, 1 woman (<1%). Subjects voided a median of 8 times in 24 hours; 95% of the subjects recorded fewer than 13 voids per 24 hours. Subjects recorded a median of 4 voids per liter of fluid intake (95% recorded fewer than 9 voids per liter intake) and a median of 5 voids per liter urine output (95% recorded fewer than 12 voids per liter output). Nighttime voids were recorded by 133 subjects (44%). According to current definitions, polyuria was present in 54 subjects (18%). Linear regression showed that the number of voids per 24 hours was related to patient age (β = .2, P< .001) and fluid intake (β = .39, P< .001). Mean (β = −.31, P< .001) and maximum (β = −.2,P = .003) voided volumes were lower among black women. Voids per liter of fluid intake varied with age (β = .19,P = .002) and were higher among parous women (β = .12, P = .003) and Asian women (β = .17, P = .002). Voids per liter output were lower among black women (β = .34, P< .001). The number of nighttime voids depended only on patient age (β = .23, P< .001). Conclusion: The results of this multiracial study differ materially from other studies of asymptomatic women. It is probably inappropriate to apply a single set of normative values to all women in the United States because of the significant variability in regional climates and populations. (Am J Obstet Gynecol 2002;187:•1384-8.)