Stage 1: normal, eGFR: > 90 ml/minute; Stage 2: mild CKD, eGFR: 60 – 89 ml/minute; Stage 3: moderate CKD, eGFR: 30 – 59 ml/minute (30 – 60% of kidney function intact) Stage 4: severe CKD, eGFR: 15 – 29 ml/minute (15 – 30% of kidney function intact) Stage 5: kidney failure, eGFR < 15 ml/minute (less than 15% of kidney function intact)