What are the KDIGO CKD G-stages?

By eGFR in mL/min/1.73 m²: G1 is 90 or above (normal/high), G2 is 60–89 (mildly decreased), G3a is 45–59, G3b is 30–44, G4 is 15–29 (severely decreased), and G5 is below 15 (kidney failure).

Is a low eGFR alone enough to diagnose CKD?

For G3a and below, a persistently reduced eGFR is sufficient. For G1 and G2, a normal or mildly reduced eGFR is only classified as CKD when there is also a marker of kidney damage such as albuminuria, haematuria, or a structural abnormality.

How is the eGFR confirmed as chronic?

Chronicity requires the abnormality to persist for at least three months. A single reduced eGFR should be repeated on a sample taken at least 90 days later before labelling the patient with chronic kidney disease.

When should I refer to nephrology?

Referral is generally indicated for G4 and G5, rapidly declining eGFR, significant or rising albuminuria, resistant hypertension, recurrent stones, or a hereditary kidney disease. Earlier referral may be appropriate with heavy proteinuria.

Why does the albuminuria category matter?

Full KDIGO classification combines the G-stage with an albuminuria category (A1 below 3, A2 3–30, A3 above 30 mg/mmol ACR) to give a heat-map of cardiovascular and kidney risk. Two patients with the same eGFR can have very different prognoses depending on albuminuria.

GFR-Based CKD Staging Tool

The GFR-based CKD staging tool maps any estimated glomerular filtration rate (eGFR) to its KDIGO chronic kidney disease G-stage and surfaces the practical implications — how often to monitor, which drugs to adjust, and when to refer. It is built for GPs, nephrologists, and pharmacists.

How it works

KDIGO divides kidney function into six bands by eGFR in mL/min/1.73 m²:

eGFR	Stage	Description
≥ 90	G1	Normal or high
60–89	G2	Mildly decreased
45–59	G3a	Mild–moderately decreased
30–44	G3b	Moderately–severely decreased
15–29	G4	Severely decreased
< 15	G5	Kidney failure

Enter the eGFR and the tool returns the matching stage, highlights it in the reference table, and shows stage-specific clinical guidance.

Reading the result

The guidance scales with severity. Early stages focus on risk-factor control and annual review; from G3a onward it prompts checks on renally-cleared drugs (metformin, DOACs, gabapentinoids), screening for anaemia and mineral-bone disorder, and progressively shorter review intervals. G4–G5 trigger nephrology referral and planning for renal replacement therapy.

Important caveats

An eGFR value alone is not the whole picture:

G1 and G2 are only CKD when a marker of kidney damage (albuminuria, haematuria, structural abnormality) is present.
Chronicity requires the abnormality to persist ≥ 3 months — confirm a reduced eGFR on a repeat sample at least 90 days apart.
Full KDIGO staging also uses an albuminuria category (A1/A2/A3) to give a combined G-and-A risk grid; two patients with identical eGFR can have very different prognoses.

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