Firstly, I have a kidney disease called Secondary Fsgs.
Many other bodybuilders do to.
If you get a blood test & it returns as high Creatinine, low efgr then the next step is to take another blood test without having trained for a couple of day's & be certain to be adequately rested & hydrated before taking the follow up test.
If your Creatinine is down & your egfr is back up in this following test, then most likely, you were dehydrated or you had trained before taking the test. If your Creatinine is still up & your egfr is down, & you think yourself as being muscular enough that your muscle mass is giving a false prediction of your egfr due to higher muscle mass/higher Creatinine levels, then get a Serum Cystatin C test done.
If Cystatin C say's that you egfr is ok, then roll with the Cystatin C as the result to use. If both your Creatinine & your serum Cystatin C show low egfr on subsequent blood follow ups then you must follow a doctors advice on what to do next. Remember there is not one single herb, vitamin, mineral, Peptide or medication available that can cure kidney disease once you have it. You can slow down it's progress, but you can't cure it.
Be sure to check your blood pressure also & if it is consistently high, then you need to get it in check with a regular low reading. Remembering that high blood pressure is one of the main drivers behind kidney disease, also heart problems.