hi doc, I am 48 yr. old man and have a history of kidney stones. recently I have had a couple of UTI s. was prescribed Bactrim. I did get an ultra sound. both kidneys, no hydronephrosis, normal cortical thickness and no calcifications. prevoid urinary bladder volume 416 mL postvoid urinary bladder 129 mL prostate gland measured 3.9 x 3.5 x 3.3 cm. is this normal for my age? I did read a normal prostate gland should measure 4 x 2 x 3 cm. could my prostate be the cause of my problems? I do often feel I have to strain a bit sometimes to urinate, also seem to drip and use toilet paper on end of my penis to shake drips. should I be worried?