1CKD Staging — KDIGO 2024
| Stage | eGFR (mL/min/1.73m²) | Description | Action |
|---|---|---|---|
| G1 | ≥ 90 | Normal or high | Monitor if risk factors present |
| G2 | 60–89 | Mildly decreased | Lifestyle modification, control BP/DM |
| G3a | 45–59 | Mildly to moderately decreased | Nephrology referral, adjust drug doses |
| G3b | 30–44 | Moderately to severely decreased | Nephrology referral, avoid nephrotoxins |
| G4 | 15–29 | Severely decreased | Prepare for renal replacement therapy |
| G5 | < 15 | Kidney failure (ESKD) | Dialysis / transplant evaluation |
* CKD diagnosis requires eGFR <60 or evidence of kidney damage (albuminuria, haematuria, imaging) for ≥3 months.
2Drug Dosing by eGFR — Quick Reference
Common drugs requiring dose adjustment in renal impairment. Use Cockcroft-Gault CrCl for drug dosing, not CKD-EPI eGFR. Always verify against current prescribing information.
| Drug | Normal Dose | CrCl 30–60 | CrCl 10–30 | CrCl <10 / Dialysis |
|---|---|---|---|---|
| Metformin | 500–1000mg BD | Use with caution; max 1g/day | Stop — lactic acidosis risk | Contraindicated |
| Metronidazole | 400mg TDS | No change | No change | Reduce dose; avoid prolonged use |
| Amoxicillin | 500mg TDS | No change | 500mg BD | 500mg OD; supplement post-HD |
| Cefixime | 400mg OD | 260mg OD (suspension) | 200mg OD | 200mg OD; no HD supplement |
| Ciprofloxacin | 500mg BD | No change | 250–500mg BD | 250–500mg OD after HD |
| Atorvastatin | 10–80mg OD | No change | Caution; start low | Caution; no specific adjustment |
| Digoxin | 0.125–0.25mg OD | Reduce 25–50%; monitor levels | Reduce 50–75% | 0.0625mg OD; avoid if possible |
| Warfarin | Dose-adjusted by INR | No change; more careful monitoring | Increase bleeding risk; monitor closely | Use with extreme caution |
| Enoxaparin (LMWH) | 1 mg/kg SC BD | No change | 1 mg/kg SC OD (reduce frequency) | Unfractionated heparin preferred |
| Tramadol | 50–100mg Q6–8H | Q8–12H | Max 200mg/day; Q12H | Avoid; metabolite accumulates |
Sources: BNF, FDA labelling, Micromedex. Use Cockcroft-Gault CrCl for drug dosing. Values are for guidance only — always verify with current prescribing information and clinical pharmacist where available.
3⚠️ Nephrotoxins — Drugs to Avoid or Use Carefully in CKD
🔴 Avoid in CKD G3b+
- NSAIDs (ibuprofen, diclofenac, naproxen)
- IV Contrast dye — hydrate well if essential
- Aminoglycosides (gentamicin, amikacin)
- Metformin (CrCl <30)
- Gadolinium MRI contrast (G4–G5)
- Lithium — narrow therapeutic index
🟡 Use with Caution — Dose Adjust
- ACE inhibitors / ARBs — monitor K⁺ and creatinine
- Spironolactone — hyperkalemia risk
- Digoxin — narrow therapeutic index
- Trimethoprim — raises creatinine (tubular secretion block)
- Herbal medicines — aristolochic acid, Ayurvedic heavy metals
- Bisphosphonates — avoid if CrCl <35
✅ Generally safe in CKD: Paracetamol (preferred analgesic), amlodipine, statins (most), azithromycin, metronidazole, most PPIs. Always review the complete medication list at each visit.
🏥 When to Refer to a Nephrologist
eGFR < 30 mL/min/1.73m² (G4–G5)
Rapid decline: >5 mL/min/1.73m²/year
Proteinuria uACR > 300 mg/g (A3)
Uncontrolled hypertension despite 3+ drugs
Unexplained haematuria with proteinuria
Hyperkalaemia (>6 mEq/L) or metabolic acidosis
CKD + anaemia not responding to iron therapy
Diabetic nephropathy with worsening proteinuria
4Formulas Used
CKD-EPI 2021 (Race-Free) — Recommended by KDIGO
// Male:
eGFR = 142 × min(Scr/0.9, 1)^−0.302 × max(Scr/0.9, 1)^−1.200 × 0.9938^Age
// Female:
eGFR = 142 × min(Scr/0.7, 1)^−0.241 × max(Scr/0.7, 1)^−1.200 × 0.9938^Age × 1.012
eGFR = 142 × min(Scr/0.9, 1)^−0.302 × max(Scr/0.9, 1)^−1.200 × 0.9938^Age
// Female:
eGFR = 142 × min(Scr/0.7, 1)^−0.241 × max(Scr/0.7, 1)^−1.200 × 0.9938^Age × 1.012
Cockcroft-Gault — Creatinine Clearance (Drug Dosing)
CrCl = [(140 − Age) × Weight(kg) × (0.85 if ♀)] ÷ [72 × Scr(mg/dL)]
MDRD 4-Variable
eGFR = 175 × Scr^−1.154 × Age^−0.203 × 0.742(if ♀)
For µmol/L: Scr (mg/dL) = Scr (µmol/L) ÷ 88.4
5Frequently Asked Questions
Key takeaway:
The CKD-EPI 2021 race-free equation is the global standard for eGFR and CKD staging, while Cockcroft-Gault remains essential for precise renal drug dosing adjustments.
Related Calculators
⚠️ Clinical Disclaimer: This calculator is intended as an aid for qualified healthcare professionals and medical students. It does not replace clinical judgment. Always verify results against patient-specific context and current clinical guidelines. Not for self-diagnosis. eGFR equations may be less accurate in extreme body weights, muscle-wasting conditions, pregnancy, and amputees.