Short-term effects of increased urine output on male bladder function and lower urinary tract symptoms.

Objectives: To determine whether the human bladder can also adapt to an increased physiologic load, because bladder dysfunction is considered to be an important factor in the development of lower urinary tract symptoms. Animal studies have shown that bladder function can be improved by increasing the urine output.

Methods: A total of 44 men between 55 and 75 years of age were asked to increase their daily fluid intake by 2 L for a 2-month period. The objective outcome measures were maximal urinary flow rate (Da Capo home uroflowmeter), maximal voided volume (frequency-volume chart), and average voided volume (frequency-volume chart). The International Prostate Symptom Score and global perceived benefit of the intervention were recorded to assess the subjective effects of the intervention.

Results: The maximal flow rate increased by 13% (2.3 mL/s), the maximal voided volume increased by 23% (93.8 mL), and average voided volume increased by 25% (60.1 mL). Of the 44 participants, 56% reported an improvement in their lower urinary tract function, but the International Prostate Symptom Score increase was statistically significant at 1.2 point.

Conclusions: The human bladder seems able to adapt to an increased load. Future randomized effectiveness studies with longer follow-up should be done to determine the upper limit of objective bladder adaptation. In addition, future studies should address the long-term efficacy in the prevention of symptoms.