Unifying Concepts

Classification and Prognosis of Chronic Kidney Disease

CKD is defined as kidney damage or glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) for 3 months or more, irrespective of cause. Kidney damage in many kidney diseases can be ascertained by the presence of albuminuria, defined as albumin-to-creatinine ratio >30 mg/g in two of three spot urine specimens.

Chronic kidney disease classification based upon glomerular filtration rate and albuminuria

GFR stages GFR (mL/min/1.73 m2) Terms
G1 ≥90 Normal or high
G2 60 to 89 Mildly decreased
G3a 45 to 59 Mildly to moderately decreased
G3b 30 to 44 Moderately to severely decreased
G4 15 to 29 Severely decreased
G5 <15 Kidney failure (add D if treated by dialysis)
Albuminuria stages AER (mg/day) Terms
A1 <30 Normal to mildly increased (may be subdivided for risk prediction)
A2 30 to 300 Moderately increased
A3 >300 Severely increased (may be subdivided into nephrotic and nonnephrotic for differential diagnosis, management, and risk prediction)

The cause of CKD is also included in the KDIGO revised classification but is not included in this table.
GFR: glomerular filtration rate; AER: albumin excretion rate; CKD: chronic kidney disease; KDIGO: Kidney Disease Improving Global Outcomes.

Prognosis of CKD by GFR and Albuminuria Categories

Prognosis of CKD by GFR and Albuminuria Categories:
KDIGO 2012
Persistent albuminuria categories
Description and range
A1 A2 A3
Normal to mildly
<30 mg/g
<3 mg/mmol
30-300 mg/g
3-30 mg/mmol
>300 mg/g
>30 mg/mmol
GFR categories (ml/min/ 1.73 m2)
Description and range
G1 Normal
or high
G2 Mildly
G3a Mildly to moderately
G3b Moderately to
severely decreased
G4 Severely
G5 Kidney

Green: low risk (if no other markers of kidney disease, no CKD); Yellow: moderately increased risk; Orange: high risk; Red, very high risk.



  1. National Kidney Foundation. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis. 2002 Feb;39(2 Suppl 1):S1-266. [Medline]
  2. Levey AS, Eckardt KU, Tsukamoto Y, Levin A, Coresh J, Rossert J, De Zeeuw D, Hostetter TH, Lameire N, Eknoyan G. Definition and classification of chronic kidney disease: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO). Kidney Int. 2005 Jun;67(6):2089-100. [Medline]
  3. Summary of Recommendation Statements. Kidney Int Suppl (2011). 2013 Jan;3(1):5-14. [Medline]


Created Feb 24, 2023.

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