eGFR Calculation 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 Equation?

The CKD-EPI 2021 equation is an updated version that estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This refined equation provides improved accuracy in assessing kidney function across diverse populations.

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 the non-linear relationship between creatinine and GFR, with optimized coefficients for different demographic groups based on the 2021 update.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, determining disease progression, staging kidney function, and guiding appropriate medication dosing and treatment 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). Use standardized creatinine measurements for optimal accuracy.

5. Frequently Asked Questions (FAQ)

Q1: What's new in the CKD-EPI 2021 equation?
A: The 2021 update features refined coefficients (142, -1.200, 0.9938) and gender factors (1.012) based on larger, more diverse population data for improved accuracy.

Q2: How does this compare to the original CKD-EPI equation?
A: The 2021 version provides more precise estimates across different age groups and kidney function levels, with updated coefficients reflecting contemporary population data.

Q3: What are the clinical implications of eGFR results?
A: eGFR values help classify kidney disease stages: ≥90 (normal), 60-89 (mild reduction), 30-59 (moderate), 15-29 (severe), <15 (kidney failure).

Q4: Are there population-specific considerations?
A: While the 2021 equation improves generalizability, local validation and consideration of ethnic-specific factors may be necessary in some populations.

Q5: When should confirmatory testing be considered?
A: Confirm with measured GFR (e.g., iohexol clearance) when precise assessment is critical, especially near treatment thresholds or in special populations.