Timed micturition and maximum urinary flow rate in randomly selected symptom-free males

Objective: To establish normal ranges for timed micturition, i.e. the time to void the first 100 ml, study its dependency on voided volume and age and compare it to maximum flow rate. Material and Methods: Randomly selected men from the National Register without voiding symptoms were investigated. These 58 men (aged 30-75 years) registered 1286 voidings (median 21 per person) at home with the aid of a portable uroflowmeter. Timed micturition and maximum flow rate were obtained from the same voidings. Results: An increase in timed micturition with an increase in age was confirmed. When estimating normal ranges it was sufficient to use the age groups ≤55 years and ≥56 years. Maximum flow rate is shown in nomograms with voided volume. Timed micturition had less dependency on voided volume than maximum flow rate. The normal ranges of timed micturition are ≤9 s for men aged ≤55 years and ≤15 s for those aged ≥56 years. The true median of timed micturition for men aged ≥56 years may be 6 s lower or 2.5 s higher than the value of a single measurement. Corresponding figures for maximum flow rate are 5 and 6 ml s. Conclusions: Timed micturition has a low dependency on volume and values of ≤9 s and ≤15 s are normal for men aged ≤55 years and ≥56 years, respectively.