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.