Chronic Kidney Disease (CKD) is classified into five stages — G1 through G5 — based on eGFR (estimated glomerular filtration rate). Stage G1 indicates normal kidney function with early damage markers; Stage G5 indicates kidney failure. Understanding your stage determines your treatment targets, dietary limits, medication safety thresholds, and referral timing per KDIGO 2024 guidelines.
The KDIGO (Kidney Disease: Improving Global Outcomes) 2024 guidelines classify CKD by eGFR into six GFR categories (G1–G5, with G3 split into G3a and G3b). Your eGFR is calculated from a blood test using the CKD-EPI 2021 race-neutral formula, which considers serum creatinine, age, and sex.
| Stage | eGFR (mL/min/1.73m²) | Description | Key Actions |
|---|---|---|---|
| G1 | ≥ 90 | Normal or high function with kidney damage markers (proteinuria, structural abnormality) | Identify and treat cause; cardiovascular risk reduction |
| G2 | 60 – 89 | Mildly decreased kidney function with damage markers | Slow progression; blood pressure control; protein-to-creatinine ratio monitoring |
| G3a | 45 – 59 | Mild to moderately decreased kidney function | CKD management; anemia screening; metabolic acidosis watch; dietary modifications begin |
| G3b | 30 – 44 | Moderately to severely decreased kidney function | Nephrology referral; potassium <2500 mg/day; phosphorus management; Metformin dose reduction |
| G4 | 15 – 29 | Severely decreased kidney function | Renal replacement therapy planning; potassium <2000 mg/day; phosphorus binders; very-low protein diet discussion |
| G5 | < 15 | Kidney failure — dialysis or transplant required | Initiate dialysis or proceed to transplantation; strict dietary and fluid management |
CKD staging alone does not tell the full story. The KDIGO 2024 heat-map risk matrix combines your GFR category with your albuminuria category (A1–A3) — measured as UACR (urinary albumin-to-creatinine ratio). The intersection of these two dimensions determines your overall CKD risk and management intensity.
| Category | UACR (mg/g) | Description |
|---|---|---|
| A1 | < 30 | Normal to mildly increased (optimal: <10 mg/g) |
| A2 | 30 – 300 | Moderately increased (microalbuminuria) |
| A3 | > 300 | Severely increased (macroalbuminuria / nephrotic range at >3500 mg/g) |
A patient with G3b eGFR (35 mL/min) + A3 albuminuria (UACR 450 mg/g) is in the highest risk category — the equivalent of a red-zone patient requiring immediate nephrology referral, SGLT2 inhibitor initiation (if eligible), and maximal RAASi therapy. This combination predicts CKD progression 4–5 times faster than G3b + A1 alone.
At Stages G1 and G2, the kidney architecture has early damage — proteinuria, haematuria, or structural abnormalities — but eGFR is preserved. The primary objectives per KDIGO 2024 are: identify the underlying cause (diabetic nephropathy, IgA nephropathy, hypertensive nephrosclerosis), achieve blood pressure ≤120/80 mmHg, initiate RAASi (ACE inhibitor or ARB) if proteinuria is present, and start SGLT2 inhibitors if the patient has Type 2 diabetes with CKD.
Stage G3 is when systemic complications begin to emerge. Patients develop:
Stage G4 demands urgent multispecialty coordination. Patients should be receiving education about dialysis modalities (haemodialysis vs. peritoneal dialysis), kidney transplant evaluation, and vascular access planning. Dietary targets become strict: potassium <2000 mg/day, phosphorus 800–1000 mg/day with preference for plant-based sources, and sodium <2000 mg/day. SGLT2 inhibitors remain beneficial down to eGFR ≥20 per the EMPA-KIDNEY and DAPA-CKD trials.
At G5, kidney function is insufficient to sustain life without renal replacement therapy. Three options exist: haemodialysis (in-centre or home), peritoneal dialysis (home-based, preferred for residual function preservation), or kidney transplantation (best long-term outcomes — increases life expectancy by 10–15 years compared to dialysis). Some patients elect conservative/palliative management without dialysis in consultation with their care team.
What are the 5 stages of chronic kidney disease?
CKD has 5 GFR stages per KDIGO 2024: G1 (≥90 — normal/high with damage markers), G2 (60–89 — mildly decreased), G3a (45–59 — mild to moderately decreased), G3b (30–44 — moderately to severely decreased), G4 (15–29 — severely decreased), and G5 (<15 — kidney failure). Stage G3 is split because G3b carries significantly higher risk of complications and mortality.
What eGFR level means kidney failure?
An eGFR below 15 mL/min/1.73m² defines kidney failure (Stage G5) per KDIGO 2024. Dialysis or transplantation is typically initiated at this stage, though timing depends on symptoms, fluid status, and patient preferences.
Can CKD stages improve or be reversed?
Stages G1–G2 can sometimes improve with aggressive treatment of the underlying cause. Stages G3–G5 involve irreversible structural damage, but progression can be substantially slowed with KDIGO-aligned therapy. The DAPA-CKD trial demonstrated a 39% reduction in CKD progression with dapagliflozin (SGLT2 inhibitor).
When should I be referred to a nephrologist?
KDIGO 2024 recommends nephrologist referral at eGFR <45 (Stage G3b), or earlier with rapid progression (>5 mL/min/year decline), A3 albuminuria, CKD complications (anaemia, acidosis, hyperkalemia), or diagnostic uncertainty.
What dietary changes apply at each CKD stage?
G1–G2: No specific restrictions unless cause-specific. G3a: Begin sodium restriction (<2300 mg/day), moderate protein (0.8 g/kg/day). G3b: Add potassium monitoring, phosphorus awareness, protein 0.6–0.8 g/kg/day. G4: Strict potassium <2000 mg/day, phosphorus <1000 mg/day, protein 0.6 g/kg/day. G5 pre-dialysis: Very-low protein with keto-acid supplements. Dialysis: Protein increases to 1.2 g/kg/day.
How does albuminuria affect my CKD risk?
Albuminuria (protein in urine, measured as UACR) is an independent predictor of CKD progression and cardiovascular mortality. A3 albuminuria (>300 mg/g UACR) combined with any GFR stage places you in a high-risk KDIGO category, requiring RAASi therapy, SGLT2 inhibitors (if eligible), and close follow-up every 3 months.