20yo male urinating often e.g 1-3 hrs - no history of utis. renal system ultrasound results on paper claim 'no abnormality'. what could problem be?

Urinary frequency: Renal us only helpful in diagnosing cause of frequency if bladder thickened. Problem could be: small bladder, excess fluid intake, caffeine or orange juice irritating bladder lining, overactive bladder, std, anxiety, interstitial cystitis, prostatitis, bladder or urethral abnormality or polyp. Unlikely significant if he doesn't have to urinate many times thru the night. Otherwise consult urologist.