Kidney Failure Risk Equation
2-year and 5-year risk of kidney failure requiring dialysis or transplant
🧮 Kidney Failure Risk Equation — Formula
🩺 Based on KDIGO guidelines. eGFR assumes stable steady-state serum creatinine.
📌Tangri N et al. JAMA 2011 / KDIGO CKD Guidelines 2022
📊 Quick Reference
| Input / Parameter | Description | Example Value |
|---|---|---|
| Serum Creatinine | Most recent stable serum creatinine (mg/dL) | 1.8 mg/dL |
| Age | Patient age in years | 62 years |
| Sex | Biological sex (affects κ and α constants in CKD-EPI) | Female |
| Weight (for CrCl) | Body weight in kg — use IBW if obese for Cockcroft-Gault | 70 kg |
| eGFR output | mL/min/1.73m² — for CKD staging | 42 mL/min/1.73m² |
| CKD Stage | KDIGO G1–G5 classification | Stage G3b |
| CrCl output | mL/min — for drug dose adjustment | 38 mL/min |
ℹ️ About This Calculator
The Kidney Failure Risk Equation estimates kidney function or a related renal parameter using clinically validated equations. Accurate assessment of kidney function is essential in clinical practice — it determines CKD staging and progression monitoring, guides dose adjustment of renally-cleared medications, informs decisions about contrast media administration, and identifies patients who may benefit from nephroprotective therapy or specialist referral.
Chronic kidney disease affects approximately 10% of the global population (KDIGO) and is a major risk factor for cardiovascular disease, hospitalisation, and death. Many patients remain undiagnosed because serum creatinine often appears "normal" until kidney function is substantially reduced — particularly in elderly, malnourished, or low muscle-mass patients where creatinine production is diminished. Calculated eGFR provides a more clinically meaningful assessment than creatinine alone.
The specific formula used by this calculator — whether CKD-EPI 2021, Cockcroft-Gault, MDRD, or another validated equation — is displayed in full in the Formula section below. The choice of equation matters: CKD-EPI 2021 (race-free) is the preferred equation for CKD staging per current KDIGO guidelines; Cockcroft-Gault is preferred for drug dose adjustment because it was the equation used in the pharmacokinetic studies that established drug dosing thresholds.
Critical limitation: all GFR estimation equations assume stable, steady-state serum creatinine. During acute kidney injury, creatinine is still rising and the calculated eGFR will overestimate true kidney function — sometimes dramatically. Never use a point-in-time creatinine measured during an acute illness for CKD staging or drug dosing. Wait for creatinine to stabilise (typically 2–4 weeks after resolution of the acute event) before interpreting eGFR results.
All calculations run entirely in your browser. No laboratory values, patient demographics, or clinical data entered into this tool are transmitted to any server or stored in any database. Your patient information remains completely private. The calculator works on any device — desktop, tablet, or smartphone — without installation or account creation.
The Kidney Failure Risk Equation supports clinical decision-making but does not replace specialist assessment. For eGFR <30 mL/min/1.73m², rapidly declining eGFR (>5 mL/min per year), heavy proteinuria, or CKD of uncertain aetiology, refer to a nephrologist. Complex drug dosing in advanced CKD should always be verified with a pharmacist experienced in renal dosing. For patients approaching kidney failure, early nephrology involvement enables timely preparation for renal replacement therapy.
📌Clinical Reference: Tangri N et al. JAMA 2011 / KDIGO CKD Guidelines 2022
📋 How to Use This Calculator
- 1
Obtain the serum creatinine value
Use the most recent stable serum creatinine from a reliable laboratory. Avoid using creatinine measured during acute illness, as it will not reflect true baseline kidney function.
- 2
Enter patient demographics
Input the patient's age, sex, and body weight. Different equations require different variables: CKD-EPI 2021 needs age and sex; Cockcroft-Gault also needs weight.
- 3
Select the appropriate formula
Choose CKD-EPI 2021 for CKD staging and epidemiological reporting. Use Cockcroft-Gault for drug dose adjustment, as it was the equation used in most pharmacokinetic studies.
- 4
Review the result and CKD stage
The eGFR is automatically classified into KDIGO CKD stages (G1–G5) and combined with albuminuria to determine overall risk category.
- 5
Adjust drug doses if indicated
For renally-cleared medications, use the CrCl result to check dose adjustment requirements in the product prescribing information or a drug reference such as Lexicomp or Micromedex.
🎯 When to Use This Calculator
CKD staging and monitoring
Calculate eGFR to stage chronic kidney disease (KDIGO G1–G5) and monitor disease progression at each outpatient visit.
Renal drug dose adjustment
Use CrCl (Cockcroft-Gault) before prescribing renally-cleared antibiotics, anticoagulants, or diabetes medications to calculate dose-adjusted prescriptions.
AKI assessment
Calculate eGFR change from baseline during hospital admission to diagnose and stage acute kidney injury per KDIGO AKI criteria.
Pre-contrast nephropathy risk assessment
Assess baseline kidney function before IV contrast administration to identify patients requiring pre-hydration protocols or contrast dose reduction.
Dialysis adequacy monitoring
Calculate Kt/V for haemodialysis patients to assess whether the delivered dose meets the minimum adequacy target (spKt/V ≥1.4 per KDOQI guidelines).
💡 Clinical Pro Tips
Never use eGFR calculated during an acute kidney injury for drug dosing or CKD staging. eGFR formulas assume steady-state creatinine — during AKI, creatinine is still rising and the calculated eGFR will significantly overestimate true kidney function.
For obese patients requiring weight-based drug dosing via Cockcroft-Gault, use adjusted body weight (ABW) rather than actual body weight for most drugs: ABW = IBW + 0.4 × (Actual weight − IBW). Check the specific drug's dosing guidelines, as some drugs use actual weight even in obesity.
Serum creatinine can be falsely low in elderly, malnourished, or cachectic patients despite significantly reduced kidney function. A 75-year-old with Scr 0.9 mg/dL may have an eGFR of only 55 mL/min — what appears "normal" creatinine may still indicate CKD G3a.
CKD staging requires both eGFR AND urine albumin-to-creatinine ratio (UACR). A patient with eGFR 65 (G2) and UACR ≥300 mg/g is at very high risk — the same as G4 CKD without albuminuria. Never stage CKD from eGFR alone.
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