How to Classify CKD

  • Identify cause of CKD (C)
  • Assign GFR category (G)
  • Assign albuminuria category (A)

Collectively referred to as “CGA Staging”

Assign GFR category as follows:

GFR categories in CKD
Category GFR
ml/min/1.73 m2
G1 ≥90 Normal or high
G2 60-89 Mildly decreased*
G3a 45-59 Mildly to moderately decreased
G3b 30-44 Moderately to severely decreased
G4 15-29 Severely decreased
G5 <15 Kidney failure
Abbreviations: CKD, chronic kidney disease; GFR, glomerular filtration rate.
*Relative to young adult level.
In the absence of evidence of kidney damage, neither GFR category G1 nor G2 fulfill the criteria for CKD.

Assign Albuminuria category as follows:

Albuminuria categories in CKD
Category ACR (mg/g) Terms
A1 <30 Normal to mildly increased
A2 30-300 Moderately increased*
A3 >300 Severely increased**
Abbreviations: ACR, albumin-to-creatinine ratio; CKD, chronic kidney disease.
*Relative to young adult level.
**Including nephrotic syndrome (albumin excretion ACR >2220 mg/g)

**Collectively referred to as “CGA Staging”

Identify Cause of CKD:

  • Cause of CKD is classified based on presence or absence of systemic disease and the location within the kidney of observed or presumed pathologic-anatomic findings on kidney biopsy or imaging.
  • Determining the cause of CKD distinguishes whether the patient has a systemic condition or a localized condition in the kidney such as glomerular disease because this functionality affects management.
  • It is anticipated that the cause of disease will not be known with certainty for many patients with CKD but can be either inferred or not known.
  Examples  of systemic diseases affecting the kidney Examples  of primary kidney diseases (absence of systemic diseases affecting the kidney)
Glomerular diseases Diabetes, systemic autoimmune diseases, systemic infections, drugs, neoplasia (including amyloidosis) Diffuse, focal or crescentic proliferative glomerulonephritis; focal and segmental glomerulosclerosis; membranous nephropathy, minimal change disease
Tubulointerstitial diseases Systemic infections, autoimmune, sarcoidoisis, drugs, urate, environmental toxins (lead, aristolochic acid), neoplasia (myeloma) Urinary-tract infections, stones, obstruction
Vascular diseases Atherosclerosis, hypertension, ischemia, cholesterol emboli, systemic vasculitis, thrombotic microangiopathy, systemic sclerosis ANCA-associated renal limited vasculitis; fibromuscular dysplasia
Cystic and congenital diseases Polycystic kidney disease, Alport’s syndrome, Fabry’s disease Renal dysplasia, medullary cystic disease, podocytopathies
Genetic diseases are not considered separately because some diseases in each category are now recognized as having genetic determinants.