Ways to Calculate eGFR

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 is recommended as the primary equation for eGFR 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 updated coefficients based on recent population studies.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, monitoring progression, 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 years).

5. Frequently Asked Questions (FAQ)

Q1: Why use CKD-EPI 2021 instead of older versions?
A: CKD-EPI 2021 provides improved accuracy across all GFR ranges and is based on more diverse and contemporary population data.

Q2: What are the key changes in the 2021 version?
A: Updated coefficients (142 instead of 141, -1.200 instead of -1.209), refined age exponent (0.9938), and adjusted gender multipliers.

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 to minimize dietary influences, but random samples are acceptable for clinical use.

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