The flow rate nomogram: I. Development.

In normal individuals the flow rate depends on the initial bladder volume in a non-linear fashion. A flow rate nomogram taking this relationship into account was developed as an aid in the interpretation of urinary flow rate data. With this approach excellent differentiation of normal from obstructed individuals was achieved. In addition, the variability in a single individual's flow rate over time was estimated to be relatively small and, thus, uroflowmetry may be used to identify changes in outflow resistance after medical or surgical therapy.