They are testing the filtration ability of your kidneys ie mine is now at 50% due to age and long standing diabetes with a lack of good control early on
I have regular urine tests done. I'm not sure what was abnormal in your test? For me every single test they've done on me for the past few years has been abnormal because of high leucocytes. This usually indicates infection, but it's not the case with me. I have been diagnosed with interstitial cystitis and see a urologist. I get sugar in my urine too sometimes and they check for proteins.