The same caution pertains to the next option, a urine microalbuminuria test. (2ndchance.info)
So at the least, elevated urine microalbuminuria / UPCR ratios or creatinine / SDMA levels in your elderly cat might suggest to your vet that a thyroid function test (T4) needs to be run as well. (2ndchance.info)
Read my explanation of microalbuminuria for other possible causes of protein - positive urine in your pet. (2ndchance.info)