Chronic kidney disease, like many things, is most easily defined in stages. I'm at Stage 3. My nephrologist never talks about this -- I think she's more concerned with other specific test results than this overall labeling system -- but my glomerular filtration rate (GFR) does put me at the high end of Stage 3. So my kidneys still have some spunk left in them, even though they're not filtering the waste from my blood like they should be.
A few things to note:
Healthy adults have a GFR of 140, although anything over 90 is considered good.
A GFR of less than 15 is kidney failure.
Stage 3 is in the 30-59 range.
I'm in the 50s.
This by no way gives a full picture of what's going on -- the stages were developed so that doctors have a guideline for treatment. But it lets you know where I fall on this 1-5 scale.