KDIGO Heat Map: CKD Risk by eGFR and Albuminuria
GFR category × albuminuria category = CKD risk.
How the KDIGO heat map grades CKD risk by combining eGFR and albuminuria categories.
Medically reviewed by Dr. Rishi Kumar Kafle, MBBS, MD, FASN. Last reviewed October 2026.
The KDIGO heat map grades the risk of CKD getting worse by combining two measures: the GFR category (G1-G5) and the albuminuria category (A1-A3). Two people with the same eGFR can sit at very different risk depending on how much albumin is in the urine.
The Two Axes
The KDIGO heat map has two axes. Going down the rows is the GFR category, from G1 (normal or high filtration) to G5 (kidney failure): the same CKD stages set by your eGFR. Going across the columns is the albuminuria category, which measures how much protein leaks into the urine.
Albuminuria is measured as a urine albumin-to-creatinine ratio (uACR): A1 is under 30 mg/g (normal to mildly increased), A2 is 30-300 mg/g (moderately increased), and A3 is over 300 mg/g (severely increased). The two axes capture different things. eGFR shows how much the kidneys filter, and albuminuria shows whether the filter is leaking, so reading them together gives a fuller picture than either alone.
| Category | uACR | Meaning |
|---|---|---|
| A1 | < 30 mg/g | Normal to mildly increased |
| A2 | 30-300 mg/g | Moderately increased |
| A3 | > 300 mg/g | Severely increased |
The Risk Grid
| GFR category | A1 (<30 mg/g) | A2 (30-300 mg/g) | A3 (>300 mg/g) |
|---|---|---|---|
| G1 (≥90) | Low | Moderate | High |
| G2 (60-89) | Low | Moderate | High |
| G3a (45-59) | Moderate | High | Very high |
| G3b (30-44) | High | Very high | Very high |
| G4 (15-29) | Very high | Very high | Very high |
| G5 (<15) | Very high | Very high | Very high |
Risk rises as you move down (lower eGFR) and to the right (more albuminuria). A low eGFR with normal albuminuria carries less risk than the same eGFR with heavy albuminuria.
How to Read the Four Risk Levels
The colours in the original KDIGO chart correspond to four bands of risk:
- Low (green): for example G1 or G2 with A1. Routine monitoring is usually enough.
- Moderate (yellow): such as G3a with A1, or G1-G2 with A2. Closer follow-up is sensible.
- High (orange): such as G3b with A1, G3a with A2, or G1-G2 with A3. More frequent review is typical.
- Very high (red): any G4 or G5 cell, G3b with A2 or A3, and G3a with A3. Specialist care is usually involved.
The bands describe the risk of CKD progressing and of related complications. They guide how closely to watch, and they do not predict what will happen to any one person. Your clinician sets the actual monitoring plan using these bands alongside your age, blood pressure, and overall health.
Why Two People With the Same eGFR Differ
Two people with the same eGFR can sit in different risk bands because the heat map also weighs albuminuria. Take two people, both at G3a with an eGFR of 50. One has A1 albuminuria and sits in the moderate band; the other has A3 albuminuria and sits in the very-high band. Their filtration is identical, but their risk is not, because heavy albuminuria signals active kidney damage. Looking at eGFR alone would miss this difference, which is why staging pairs the GFR category with an albuminuria category rather than relying on the filtration number on its own.
What G3a A3 and Other Common Codes Mean
Lab reports and clinic letters often shorten a position on the grid to a code such as “G3a A3”. The first part is the GFR category and the second is the albuminuria category, so each code points to one cell of the table above:
- G2 A2: eGFR 60 to 89 with a uACR of 30 to 300 mg/g, a moderate (yellow) risk cell.
- G3a A1: eGFR 45 to 59 with a uACR under 30 mg/g, also moderate (yellow).
- G3a A2: eGFR 45 to 59 with a uACR of 30 to 300 mg/g, high (orange) risk.
- G3a A3: eGFR 45 to 59 with a uACR over 300 mg/g, very high (red) risk.
- G3b A1: eGFR 30 to 44 with a uACR under 30 mg/g, high (orange) risk.
A code describes risk; it is not a diagnosis on its own. Chronic kidney disease is confirmed only when the abnormal results persist for more than three months, so a single reading is usually repeated before a cell is assigned.
What the Heat Map Does Not Decide
The KDIGO heat map grades risk; by itself, it does not set treatment or predict outcomes. A “very high” cell does not mean dialysis is imminent. The timing of dialysis depends on symptoms and eGFR, and many people in the higher-risk cells remain stable with good management. The heat map focuses attention: it tells you and your clinician how closely to monitor and how aggressively to manage the underlying causes.
How Clinicians Use the Heat Map
Clinicians use the KDIGO heat map to turn two lab results into a shared plan. Once your GFR category and albuminuria category are known, the cell where they meet suggests how often kidney function should be rechecked and whether a referral to a specialist is worth considering. A low-risk green cell usually means routine annual checks; the orange and red cells call for more frequent monitoring and tighter control of blood pressure and any underlying cause such as diabetes. The grid does not replace clinical judgement. It gives you and your clinician a common reference point for what to watch and how closely.
Tracking Your Position Over Time
Your place on the KDIGO heat map can change, and the direction matters. Improving albuminuria (often a sign that treatment of the underlying cause is working) can move you to the left, into a lower-risk column, even if your eGFR is steady. A falling eGFR moves you down into a higher-risk row. Because both axes can shift, the most useful view is your trend across several results rather than a single snapshot. Re-checking both measures periodically lets your care team see whether the picture is stable, improving, or in need of a change in management.
Measure Your Albuminuria
Use the UACR calculator to find your A category, then read it against your GFR stage. Together they place you on the grid above. If you do not yet know your filtration, estimate it with the eGFR calculator first.