The question might be to consider what does a diagnosis change in terms of how you go on with your life? You could have a doctor who told you that you had an early and mild stage of CKD. If you heard that from your doctor, how would that change your life? I would say that I would probably want to eat a careful and nutritionally sound diet in either case. It sounds like you are not having any symptoms that require medication treatment so there would be no reason to start you on anything you aren't already taking, even if he called it early stage CKD. I would pay close attention to my labs to see if there is anything that is borderline (particularly minerals like potassium). Likewise monitor you blood pressure frequently. Other than that, why not just work with your doctor and see where this goes? What difference does it make if we call it age related kidney decline or CKD? How does it change your life either way?