CKD Staging Calculator (KDIGO GFR and Albuminuria)
Stage chronic kidney disease using the KDIGO framework, which combines GFR category (G1–G5) with albuminuria category (A1–A3) into a combined risk classification.
🧪 Clinical Reference📐 Stage = GFR category × albuminuria category (KDIGO heat map)🏥 Health
eGFR (mL/min/1.73m²)
Urine ACR (mg/g)
Duration of abnormality
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| CKD Staging Calculator (KDIGO GFR and Albuminuria) | — | Stage = GFR category × albuminuria category (KDIGO heat map) | stage |
Step-by-Step Examples
Example 1
Early CKD
eGFR 72, ACR 15 mg/g, present over 3 months.
- eGFR 60–89 → G2
- ACR under 30 → A1
- G2 A1 sits in the low-risk band
- Note: G2 A1 alone is not CKD without other damage markers
✓ Stage G2 A1 — low risk
Example 2
Moderate CKD
eGFR 52, ACR 45 mg/g, present over 3 months.
- eGFR 45–59 → G3a
- ACR 30–300 → A2
- G3a A2 falls in the high-risk band
✓ Stage G3a A2 — high risk
Example 3
Advanced CKD
eGFR 26, ACR 480 mg/g.
- eGFR 15–29 → G4
- ACR above 300 → A3
- G4 A3 sits in the very-high-risk band
✓ Stage G4 A3 — very high risk
Real-World Applications
Nephrology Referral
KDIGO risk category, not eGFR alone, drives referral thresholds and monitoring frequency.
Two-Dimensional Risk
Albuminuria adds prognostic information independent of GFR, which is why the heat map uses both axes.
Medication Review
Stage determines which drugs need dose adjustment and which should be avoided altogether.
Progression Monitoring
Tracking movement across the grid over time reveals progression more clearly than either measure alone.
Common Mistakes to Avoid
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Staging on GFR alone
A patient with normal GFR but heavy albuminuria can be at higher risk than one with modestly reduced GFR and no albuminuria. Both axes are required.
⚠️
Diagnosing CKD from a single measurement
The chronicity criterion — abnormality persisting beyond three months — is part of the definition. A single low eGFR may be acute kidney injury.
⚠️
Assuming G1 or G2 with A1 means CKD
Categories G1 and G2 with normal albuminuria are not CKD unless other markers of kidney damage, such as structural abnormality or histology, are present.
Frequently Asked Questions
How is chronic kidney disease staged? ▾
Using the KDIGO framework, which combines six GFR categories (G1 to G5) with three albuminuria categories (A1 to A3) into a combined risk classification.
Why does albuminuria matter for staging? ▾
Albuminuria independently predicts progression and cardiovascular events. Two patients with identical GFR can face very different risk depending on their albuminuria.
What is the difference between G3a and G3b? ▾
G3a is an eGFR of 45–59 and G3b is 30–44. Stage 3 was split because outcomes differ meaningfully between the two halves of the old range.
Does CKD always progress? ▾
No. Many people with early CKD remain stable for years, particularly with blood pressure control, glycaemic management, and appropriate medication.
Why must the abnormality last three months? ▾
To distinguish chronic kidney disease from acute kidney injury, which is often reversible and requires entirely different management.