Uroflow nomogram for male adolescents.

Purpose: Uroflowmetry is well established for investigating lower urinary tract symptoms. Current nomograms are based on sample sizes limited to 8 men of the same age. We generated percentile curves for the maximum urinary flow rate (Qmax) in relation to voided volume in male adolescents in a large homogenous healthy group.

Materials And Methods: A total of 348 males who were 18 years old were investigated, excluding probands with a urological history. Only samples with a voided volume of 150 cc or more were included. One micturition was obtained per proband to determine Qmax, the average urinary flow rate, time to Qmax and volume. Resulting curves were compared with nomograms for children and adults.

Results: Average voided volume +/- SD was 262 +/- 91.9 cc (range 151 to 664). Qmax was 28.4 +/- 9.7 cc per second (range 11.4 to 76) with an average urinary flow rate of 18.6 +/- 5.5 cc per second (range 4 to 44), a micturition time of 16.9 +/- 6.8 seconds (range 7 to 48) and a mean time to Qmax of 7.8 +/- 4.1 seconds (range 1 to 25). A total of 341 probands had a Qmax of more than 15 cc per second, while only 7 showed a Qmax of less than 15 cc per second. At up to 350 cc Qmax increased with volume, followed by a plateau phase at 350 to 550 cc and a Qmax decrease at higher volumes.

Conclusions: Voiding volumes in a large homogenous adolescent group demonstrated optimal Qmax at voiding volumes between 350 and 550 cc with a decrease at higher volumes. Therefore, uroflow studies in adolescent males should be interpreted with caution at volumes less than 350 and more than 550 cc.