Maximum and average urine flow rates in normal children--the Miskolc nomograms.

OBJECTIVE: To establish normal reference ranges of urinary flow rates in children. SUBJECTS AND METHODS: From a screening programme, 200 healthy children (96 girls and 104 boys, between 3 and 18 years old) with no renal, urological, psychological or neurological disorders were selected, and they provided 433 micturitions for analysis. The children were divided into those with body surface areas of < 0.92 m2, between 0.92 and 1.42 m2 and > 1.42 m2. The voided volume, maximum and average flow rates of urine were measured. Data were fitted by several mathematical functions and goodness-of-fit determined.
RESULTS: The relationship between maximal or average flow rates and voided volume was best fitted by a logarithmic function. The maximal and average urine flow rate nomograms are given in centile form for each body surface area group in both girls and boys. Flow rates showed a close relationship with voided volumes in both sexes and for all body sizes. The average maximal and average flow rates were higher in girls than in boys.
CONCLUSION: Normal nomograms of maximal and average urine flow rates of girls and boys at three different body surfaces are presented in centile form. These may be useful for diagnosing lower urinary tract disturbances in children over a wide range of body size and voided volumes.