Maximum voided volume (MVV, formerly known as functional bladder capacity) is a key determinant of daytime and nighttime lower urinary tract symptoms (LUTS) in both men and women. In recent years, body mass index (BMI) has been recognized as an important parameter in the evaluation of polyuria, defined by the International Continence Society (ICS) as 24 hour urine production >40 mL/kg. Conversely, MVV, which is used to delineate nocturia owing to diminished bladder capacity, has not been interpreted in the context of height and weight. Previous studies have instead detailed the association between MVV and LUTS. 
The primary aim of this study was to determine the potential relationship between MVV, height, and weight.

We performed a post hoc analysis of voiding diary data obtained from the Krimpen study, a large community-based study of Dutch men aged 50-78 years. A total of 1,688 men were included at baseline. MVV, defined as the single largest voided volume recorded on the 24 hour voiding diary, was compared to BMI (kg/m2), height (m), and weight (kg) through simple and multiple linear regression analyses. Adjustments were made for International Prostate Symptom Score (IPSS) and age.

Simple linear regression analyses revealed a significant positive correlation between MVV and both height (B = 305.65, p<0.001) and weight (B = 1.33, p = 0.001). Smaller MVV was strongly correlated with higher age (B = -2.66, p<0.001) and self-reported LUTS as determined by the IPSS (B = -5.18, p<0.001). MVV had no association with BMI (B = 1.31, p = 0.348). After adjustment, multiple linear regression analysis demonstrated that height was a stronger physiologic predictor of MVV (B = 232.87, p = 0.002) when compared to weight (B = 0.50, p = 0.253).

In the present study, MVV was found to be independently correlated with height but showed no association with weight or BMI. Decreases in MVV were correlated with increases in age and increases in IPSS score, as documented in previous studies [1].

Height should be considered in the interpretation of MVV values to further individualize the evaluation and management of nocturia and nocturnal polyuria. New parameters may use patient height and 24 hour urine production instead of patient weight or BMI. This change can aid in improving diagnostic accuracy and subsequent treatment plans. It is postulated that height is a fixed anatomic characteristic likely related to internal organ size while weight fluctuates with variation in diet and caloric expenditure.

van Doorn, B., & Bosch, J. L. H. R. (2012). Diary-Based Population Analysis of Nocturia in Older Men: Findings of the Krimpen Study. In M. Weiss FACS, Jeffrey P., M. Blaivas Jerry G., M. Van Kerrebroeck PhD, MMSc, Philip E. V., & M. Wein FACS, PhD(hon), Alan J. (Eds.), Nocturia: Causes, Consequences and Clinical Approaches (pp. 59–75). Springer. https://doi.org/10.1007/978-1-4614-1156-7_4