The stages of chronic kidney disease are mainly based on measured or estimated GFR (Glomerular Filtration Rate).
There are five stages, but kidney function is normal in Stage 1, and minimally reduced in Stage 2.
This term "advanced kidney disease" predominantly refers to those in late Stage 4 and Stage 5, either on renal replacement therapy, being prepared for this treatment, or having opted not to undergo it.
Stages of chronic kidney disease
Stage 1. Normal or increased GFR, with other evidence of kidney damage. GFR > 90 ml/min
Stage 2. Slight decrease in GFR, with other evidence of kidney damage. GFR: 60 - 90 ml/min
Stage 3 A. Moderate decrease in GFR, with or without other evidence of kidney damage. GFR: 45 - 60 ml/min
Stage 3 B. Moderate decrease in GFR, with or without other evidence of kidney damage. GFR: 30 - 45 ml/min
Stage 4. Severe decrease in GFR, with or without other evidence of kidney damage. GFR: 15 - 30 ml/min
Stage 5. Established renal failure. GFR: < 15 ml/min
All GFR values are normalized to an average surface area of 1.73 m2 Adapted from The Renal Association 2013, CKD stages. Internet. Accessed on April 25, 2016.