Its very important to consider your kidneys. Unfortunately there isnt much you can do... But most importantly, keep your blood pressure down, drink water.
Your creatinine and gfr indicate your bodies ability to filter waste, its important to check when having your blood panel. For individuals who carry more muscle mass your creatine will be higher, but in doing so your risk of kidney failure raises. My creatinine is currently 1.37 which puts me in stage 2 kidney failure... i think the normal range is .6-1.27. The biggest way this level is altered is by hypertension (blood pressure). Hence the reason you should check your BP while on so you can regulate it.
Some studies suggest that you cant improve your creatinine once its raised you can only treat it. My creatinine has gone down from 1.55, by reducing my BD, but it hasnt gone much lower from there.
Hope this info helps....