An insurance referral may be required by the insurance to see a specialist. Call the insurance to find out if "a referral is required to see a specialist".

If not an insurance issue, the doc can just simply refer/request you to the urologist by calling to make the appt to get your foot in the door. I have called the GP's office, letting them know my concerns and that I'd like a second opinion with a urologist, and asked them to set it up.

The urologist would go over your medical history and symptoms; will discuss this with you and you two together will decide from there: testing & treatment options, etc. or other options.

I am a firm believer in second opinions. It is your health that matters most. Good luck.