You would be on dialysis if your estimated GFR is truly 4.2. But doubt it. It may be 42. Are you white or African American? That is the meaning of AfAm. It means the calculation is for non whites. NonAfAm means the calculation is for whites. They are calculated differently, for race because the kidney function of a white person is different than non whites. I don’t understand why, but there it is. Go back and look again at the estimated GFR on the lab result. They should be giving you also, the Stages of kidney failure for different ages. A lot goes into the calculation. As we age, the estimated GFR goes down, because it’s normal to lose kidney function gradually, over time. Ask your doctor what all this means. Yes, if you do in fact have Stage 3, you need to adjust your diet, know why your kidneys are failing, and what you can do to help them. I have been in Stage 3 for at least fifteen years. I knew I hurt my kidneys by not controlling my blood pressure very well. So, I learned what to do. I cut my protein intake, I cut my sodium way down to below 1000 mg a day. I am a compulsive label reader. Nobody can help you unless you are willing to learn and help yourself.