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GFR (Glomerular Filtration Rate) Calculator

Calculate Kidney Function (eGFR) using MDRD, CKD-EPI (2009 & 2021), and Cockcroft-Gault formulas. Includes CKD staging and severity analysis.

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About

Assessment of renal function relies heavily on the Glomerular Filtration Rate (GFR), a metric representing the flow volume of filtered fluid through the kidney. Direct measurement involves invasive procedures, so clinical practice utilizes estimated GFR (eGFR) based on serum biomarkers like creatinine. Accurate estimation dictates treatment dosing, contrast imaging safety, and Chronic Kidney Disease (CKD) staging.

This tool aggregates the primary clinical algorithms used in nephrology. The CKD-EPI 2021 equation removes race as a variable, aligning with current medical equity standards. The MDRD study equation remains relevant for specific historical comparisons, while Cockcroft-Gault is frequently utilized for drug dosing adjustments. The interface automatically flags CKD stages 1 through 5 based on the calculated output, providing immediate visual feedback on renal impairment severity.

gfr kidney function egfr nephrology ckd stage creatinine

Formulas

The calculation logic employs three distinct mathematical models.

1. CKD-EPI (2021 Refit):

eGFR = 142 × min(Scrκ, 1)α × max(Scrκ, 1)-1.200 × 0.9938Age × 1.012 [if Female]

Where Scr is serum creatinine, κ is 0.7 (F) or 0.9 (M), and α is -0.241 (F) or -0.302 (M).

2. MDRD (IDMS-traceable):

eGFR = 175 × (Scr)-1.154 × (Age)-0.203 × 0.742 [if Female] × 1.212 [if Black]

3. Cockcroft-Gault:

ClCr = (140 − Age) × Weight72 × Scr × 0.85 [if Female]

Reference Data

CKD StageGFR Range (mL/min/1.73m2)Clinical DescriptionAction
Stage 1≥ 90Normal or high functionObserve, control risk factors
Stage 260 - 89Mildly decreasedEstimate progression
Stage 3a45 - 59Mild to moderateTreat complications
Stage 3b30 - 44Moderate to severeTreat complications
Stage 415 - 29Severely decreasedPrepare for replacement
Stage 5< 15Kidney failureDialysis or transplant

Frequently Asked Questions

CKD-EPI was developed to improve accuracy at higher GFR levels (above 60 mL/min/1.73m²), where MDRD often underestimates function. For lower GFR values, they tend to align more closely.
The Cockcroft-Gault formula is traditionally used for drug dosing adjustments (e.g., antibiotics, NOACs) because many pharmacokinetic studies were originally validated using this method, although CKD-EPI is increasingly accepted.
The 2021 equation removes the "Race" coefficient. Previously, the 2009 equation adjusted GFR upward for Black patients. The 2021 refit eliminates this adjustment to prevent potential inequities in care and transplant eligibility.
Yes. Select the unit in the dropdown. The tool internally converts µmol/L to mg/dL (by dividing by 88.4) before processing the algorithm.