Table 1.

— National Kidney Foundation Kidney Disease Outcomes Quality Initiative Definitions of CKD

CKD Stage	Definition
1	Normal GFR (> 90 mL/min/1.73 m2) with persistent kidney damage (eg, albuminuria)
2	GFR between 60 and 89 mL/min/1.73 m2 with persistent kidney damage (eg, albuminuria)
3	GFR between 30 and 59 mL/min/1.73 m2
4	GFR between 15 and 29 mL/min/1.73 m2
5	GFR < 15 mL/min/1.73 m2 or end-stage renal disease

The table displays the consensus classification of CKD, in which CKD is defined by either a decrease in GFR or the presence of kidney damage typically quantified as abnormal protein excretion. CKD = chronic kidney disease; GFR = glomerular filtration rate.