tomarctus: The urologist will have you do a urine flow test. You have to tank up beforehand with a lot of water. Then you get an ultrasound of your full bladder, pressing against it. That one is really fun when you're ready to burst. Then you piss it all out into a funnel with a bucket underneath and the flow rate is measured. Then you get another ultrasound empty.
My urologist was astounded at my capacity. He asked me if I always piss that much. I said "no, I just drank a lot of water like you requested". I can hold plenty but I usually piss every 2 hours.
As Pekcer said you will give a urine specimen and blood specimen unless you already had that done at your internist. Plus all the questions about diet, and so forth. I agree with him. Make an appointment. At least it might put your mind at ease if nothing serious is going on.