How Can We Calculate GFR

CKD-EPI 2021 Creatinine Equation Calculator

CKD-EPI 2021 Equation:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Estimated GFR (eGFR):

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1. What is the CKD-EPI 2021 Creatinine Equation?

The CKD-EPI 2021 (Chronic Kidney Disease Epidemiology Collaboration 2021) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This updated version provides improved accuracy and removes race as a variable in the calculation.

2. How Does the Calculator Work?

The calculator uses the CKD-EPI 2021 equation:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Where:

\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male)
\( \alpha \) — -0.241 (female) or -0.302 (male)
\( age \) — Age in years
1.012 — Female multiplier

Explanation: The equation accounts for non-linear relationship between creatinine and GFR, with different coefficients for different demographic groups. The 2021 version uses updated coefficients for improved accuracy.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, monitoring kidney function over time, and guiding medication dosing decisions.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. All values must be valid (creatinine > 0, age between 1-120). Use fasting serum creatinine values for most accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What's new in the CKD-EPI 2021 equation?
A: The 2021 version uses updated coefficients, removes race as a variable, and provides improved accuracy across diverse populations.

Q2: Why was race removed from the equation?
A: Race was removed to eliminate potential health disparities and provide more equitable kidney function assessment across all populations.

Q3: What are normal eGFR values?
A: Normal is generally ≥90 mL/min/1.73m², though values naturally decline with age. Below 60 for 3+ months indicates chronic kidney disease.

Q4: When should creatinine be measured?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise which can temporarily elevate creatinine.

Q5: Are there limitations to this equation?
A: Less accurate in extremes of age/weight, amputees, pregnant women, those with rapidly changing kidney function, and individuals with unusual muscle mass.