Realise this is an old post and apologies for bumping. From what I understand though - and I'm not claiming to be an expert - having high creatinine levels is expected when taking creatine but doesn't mean there is any impaired kidney function. The body produces creatine naturally but it is filtered through your kidneys, converted into creatinine and pissed out. Whereas creatine tablets/powder divert and store more of it in your muscles instead to provide more energy, so you will naturally have higher creatinine levels from the creatine that is stored. It doesn't mean your kidneys aren't working, it means you've got more creatine stored in your body.
My wife has a kidney transplant due to renal failure. She has creatinine levels tested every few months as this is the main way of checking kidney function (if the kidney wasn't working it wouldn't filter her natural creatine and therefore higher creatinine). If she took creatine her creatinine levels would elevate further which would render the creatinine tests useless and there's be no way of knowing whether her kidney was functioning OK. But unless you're concerned you have kidney disease there's no reason to worry about the higher creatinine levels when taking creatine.