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eGFR Calculator — CKD-EPI 2021

CKD-EPI Creatinine 2021 equation · Race-free formula · CKD staging (G1–G5) · Drug dosing guidance · KDIGO 2024 standards

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Uses the 2021 CKD-EPI Creatinine equation — the current international standard.
Normal: ~60–110 μmol/L (0.7–1.2 mg/dL)
2021 CKD-EPI equation is race-free. Sex at birth used for creatinine reference range.
📐 2021 CKD-EPI Formula
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938Age × 1.012 [if female]
κ = 0.7 (F) / 0.9 (M) · α = −0.241 (F) / −0.302 (M)
Levey AS et al. NEJM 2021. Race-free update.
⚠️ eGFR is an estimate. Not validated in pregnancy, extremes of muscle mass, acute kidney injury or children under 18. Use clinical judgement alongside eGFR.
eGFR Result
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Enter creatinine, age and sex
Normal eGFR: ≥ 60 mL/min/1.73m²

eGFR CKD-EPI 2021: The Complete Clinical Guide

Why the 2021 update matters, CKD staging, drug dosing by eGFR, race-free equation, and when to refer

What Is eGFR and Why Use CKD-EPI 2021?

Estimated Glomerular Filtration Rate (eGFR) measures kidney filtration capacity, reported in mL/min/1.73m² standardised to body surface area. The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) 2021 equation is the current international standard, replacing both the older MDRD equation and the original 2009 CKD-EPI equation.

The 2021 update removed race as a variable — the previous 2009 equation applied a 1.159 multiplier for patients identified as Black, which has been widely criticised for being biologically unjustified, introducing systematic bias, and potentially delaying referral and transplant listing in Black patients with CKD. The 2021 race-free equation is endorsed by KDIGO, NKF, NICE, and ASN.

Why eGFR vs Creatinine Clearance (Cockcroft-Gault)?
CKD-EPI eGFR is preferred for CKD staging and monitoring. Cockcroft-Gault (CrCl) is still preferred for drug dosing in many guidelines because most pharmacokinetic studies were conducted using CrCl. Both calculators are available on MedDraftPro — use eGFR for staging, CrCl for drug dosing unless your local guideline specifies eGFR.

CKD Staging by eGFR (KDIGO 2024)

StageeGFR (mL/min/1.73m²)DescriptionAction
G1≥ 90Normal or highCKD only if other markers present. Monitor.
G260–89Mildly decreasedMonitor annually if CKD confirmed.
G3a45–59Mild–moderate decreaseMonitor 6-monthly. Check ACR, BP, anaemia.
G3b30–44Moderate–severe decreaseMonitor 3–6 monthly. Nephrology input. Optimise CVD risk.
G415–29Severely decreasedNephrology referral. RRT planning. Vaccinations.
G5< 15Kidney failureRRT (dialysis/transplant) or conservative management.

Key Drug Dose Adjustments by eGFR

Many commonly prescribed medications require dose adjustment or avoidance in CKD. The following are the most clinically important:

DrugeGFR ThresholdAction Required
Metformin< 45 / < 30Review risk at <45; stop at <30 (lactic acidosis risk)
NSAIDs< 60Avoid — worsen renal function and cause fluid retention
SGLT2 inhibitors< 20 (glycaemic) / <25 (HF/CKD)Check individual drug SPC — thresholds vary by indication
Direct oral anticoagulantsVaries by drugApixaban preferred in CKD; avoid dabigatran if CrCl <30
Digoxin< 30Reduce dose; monitor levels — narrow therapeutic index
Low molecular weight heparin< 30Dose reduce or switch to UFH; monitor anti-Xa levels

Also Try: Creatinine Clearance Calculator

Use Cockcroft-Gault CrCl for drug dosing, eGFR CKD-EPI for CKD staging.

CrCl Calculator →

Frequently Asked Questions

What is the difference between eGFR and GFR?

True GFR requires inulin clearance or iothalamate measurement — impractical for routine clinical use. eGFR is estimated from serum creatinine, age, and sex using validated equations. CKD-EPI 2021 eGFR is accurate within ±30% of true GFR in approximately 90% of patients. For most clinical decisions, eGFR is sufficiently accurate and far more practical.

When is eGFR unreliable?

eGFR is unreliable in acute kidney injury (creatinine not yet at steady state), extremes of muscle mass (amputees, bodybuilders, cachexia, cirrhosis), pregnancy (increased GFR throughout), vegetarian diet (lower creatinine generation), and patients with very high or low creatinine from non-renal causes. In these situations, use 24-hour urine creatinine clearance or cystatin C-based eGFR.

Why does the 2021 equation not include race?

The 2009 CKD-EPI equation included a 1.159 multiplier for patients identified as Black, based on observed population differences in creatinine levels attributed to muscle mass differences. This has been criticised as biologically unjustified, reinforcing harmful racial categories in medicine, and causing real harm by delaying transplant referral for Black patients. The 2021 update removed this variable following a joint NKF-ASN task force recommendation, without significantly reducing overall accuracy.

References

  1. Inker LA, Eneanya ND, Coresh J, et al. New Creatinine– and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737-1749.
  2. KDIGO 2024 CKD Guideline. Kidney International Supplements. 2024.
  3. NICE NG203. Chronic kidney disease: assessment and management. 2021.
  4. Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate GFR. Ann Intern Med. 2009;150(9):604-612.

⚠️ Medical Disclaimer: eGFR is an estimate for clinical decision support only. It is not validated in AKI, pregnancy, or children. Always interpret with full clinical context. MedDraftPro accepts no clinical liability.

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