CKD stages – reference guide

This quick reference guide outlines the diagnostic criteria for Chronic Kidney Disease (CKD) and the eGFR/ACR thresholds for the different CKD stages.

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CKD definition

Chronic kidney disease (CKD) is defined as abnormalities of kidney function or structure present for more than 3 months, with implications for health. This includes all people with markers of kidney damage and those with a glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m2 on at least 2 occasions separated by a period of at least 90 days (with or without markers of kidney damage).1

Markers of kidney disease may include: albuminuria (ACR > 3 mg/mmol), haematuria (of presumed or confirmed renal origin), electrolyte abnormalities due to tubular disorders, renal histological abnormalities, structural abnormalities detected by imaging (e.g. polycystic kidneys, reflux nephropathy) or a history of kidney transplantation.2

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CKD staging

CKD is classified according to estimated GFR (eGFR) and albumin:creatinine ratio (ACR), using 'G' to denote the GFR category and 'A' for the ACR category, for example:1

  • A person with an eGFR of 25 ml/min/1.73 m2 and an ACR of 15 mg/mmol has CKD G4A2.
  • A person with an eGFR of 50 ml/min/1.73 m2 and an ACR of 35 mg/mmol has CKD G3aA3.
  • An eGFR of less than 15 ml/min/1.73 m2 (GFR category G5) is referred to as kidney failure.

Be aware that:1

  • Increased ACR is associated with increased risk of adverse outcomes
  • Decreased GFR is associated with increased risk of adverse outcomes
  • Increased ACR and decreased GFR in combination multiply the risk of adverse outcomes.

CKD stages – eGFR1,3Diagram of CKD stages according to eGFR values | OnMedica | CKD staging reference guide

eGFR
(ml/min/1.73 m2)

Stages
≥ 90 Stage 1 (G1) – normal eGFR, but other tests have detected signs of kidney damage
60 to 89 Stage 2 (G2) – slightly reduced eGFR with other signs of kidney damage
45 to 59 Stage 3a (G3a) – mild to moderate reduction
30 to 44 Stage 3b (G3b) – moderate to severe reduction
15 to 29 Stage 4 (G4) – severe reduction
< 15 Stage 5 (G5) – the kidneys have lost almost all of their function


CKD stages – ACR1,3

ACR (mg/mmol) Stages
< 3 A1 – normal to mildly increased
3 to 30 A2 – moderately increased
> 30 A3 – severely increased


For both eGFR and ACR, a higher stage indicates more severe kidney disease.

Risk of adverse outcomes in adults by GFR and ACR stages (based on NICE guidance1)

 

A1

A2

A3

G1

Low risk

No CKD if there are no other markers of kidney damage

Moderate risk

High risk

G2

Moderate risk

High risk

G3a

Moderate risk

High risk

Very high risk

G3b

High risk

Very high risk

Very high risk

G4

Very high risk

Very high risk

Very high risk

G5

Very high risk

Very high risk

Very high risk

 


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>> Read our summary of the key changes that GPs should know.

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References

  1. Chronic kidney disease in adults: assessment and management. NICE CG182, updated 2015.
  2. CKD Stages. The Renal Association. [accessed February 2021]
  3. Chronic kidney disease – Diagnosis. NHS website, 2019.

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