altitude should not effect your ability to urinate. you may have an enlarged prostate (common at age 66) and difficulty urinating is common. at any altitude.
how does higher altitude affect urnation? . i am going to tahoe and yosemite to around 6 000 to 8000 feet. i am 66 and have slowed urination and sometimes have problems on international flights at altitude in a pressurized cabin. i normally live in dallas. .