Normal peak urinary flow rates obtained from small voided volumes can provide a reliable assessment of bladder function.

The urinary flow rates of 3 normal men were measured for a wide range of bladder volumes. Linear transformation of voiding curve data indicated that the relationship between urinary flow and voided volume could be described as parabolic, hyperbolic or logarithmic. These functional relationships were found to hold irrespective of age and volume, although deviations from the calculated voiding curves occurred at higher volumes. If only voiding data for volumes less than 150 ml. were considered, then, in addition to the aforementioned mathematical relationships, the dependence of flow on volume could be described validly by a straight line function, the slope of which represents an individual's best possible voiding potential.