Table 1.

US National Kidney Foundation Kidney Disease Quality Outcomes Initiative classification of stages of chronic kidney disease⁷

Stage	Description	Glomerular filtration rate in ml/min/1.73 m2
1	Kidney damage with normal or high GFR	≥90
2	Kidney damage with slightly low GFR	60-89
3	Moderately low GFR	30-59
4	Severe low GFR	15-29
5	Kidney failure	<15 or dialysis

GFR=glomerular filtration rate.

Chronic kidney disease is defined as either kidney damage or glomerular filtration rate <60 ml/min/1.73m² for ≥3 months. Kidney damage is defined as pathological abnormalities or markers of damage, including abnormalities in blood or urine tests or imaging studies.