NATURAL-HISTORY OF PROSTATISM - URINARY FLOW-RATES IN A COMMUNITY-BASED STUDY

Urinary flow rates were measured in a randomly selected community samp le of more than 2,000 men 40 to 79 years old with no history of prosta te surgery, prostate cancer or certain other diseases known to interfe re with normal voiding. Peak urinary flow rates decreased from a media n of 20.3 ml. per second in men 40 to 44 years old to 11.5 ml. per sec ond for men 75 to 79 years old, while voided volumes decreased from a median of 355.5 to 222.5 ml. for the same age ranges. Peak flow rates of less than 10 ml. per second were found in 6% of the men aged 40 to 44 years, increasing to 35% among men aged 75 to 79 years. Urological standards for peak urinary flow rate should be based on community data , and should account for age and voided volume. Our study may serve as the starting point for the development of community-based flow rate n ormal ranges. Nomograms are given to permit estimating flow rate perce ntiles as a function of age and voided volume.