Increased bladder mass occurs as a consequence of bladder outlet obstruction in animals and patients, and relief of bladder outlet obstruction reverses an increased bladder mass. Whether increased bladder mass is not only a consequence of bladder outlet obstruction but also a relevant risk factor for the progression of lower urinary tract symptoms associated with benign prostate hyperplasia cannot be decided due to a lack of appropriate data, most likely because bladder wall thickness is not routinely measured in clinical studies and/or routine clinical practice. Despite this lack of data, many urologists feel that increased bladder mass should be prevented or decreased to reduce the occurrence of serious complications.

The possibility of using bladder wall thickness data as criteria for benign prostate hyperplasia intervention and as outcome criteria for benign prostate hyperplasia treatment has been proposed. Detrusor hypertrophy associated with bladder outlet obstruction can be imaged on suprapubic ultrasound, and bladder mass can be quantified from the evaluation of bladder wall thickness and bladder volume. Bladder wall hypertrophy has been found to be correlated with detrusor function.

Independent studies have shown that surgical treatment of benign prostatic obstruction results in a significant decrease of bladder mass. Preliminary data suggest the possibility that medical treatment with alpha-adrenergic antagonists might also produce a reduction of bladder wall hypertrophy.

The investigators assume that the prevention of benign prostate hyperplasia progression by alpha-adrenergic antagonists and 5 alpha reductase inhibitors may be result of bladder function protection. To our knowledge there have been no studies that evaluated the effects of a 5 alpha reductase inhibitors on bladder function. Therefore, the investigators plan to conduct a prospective trial evaluating the effects of 5 alpha reductase inhibitors on bladder function by the evaluation of bladder wall thickness and lower urinary tract symptoms.