National Kidney GFR 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 National Kidney GFR Calculator?

The National Kidney GFR Calculator uses the CKD-EPI 2021 equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, and sex. This updated 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 incorporates updated coefficients based on recent research, providing more precise GFR estimation while accounting for demographic variations.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for early detection of chronic kidney disease, monitoring disease progression, and guiding clinical decisions regarding medication dosing and treatment strategies.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Ensure all values are valid (creatinine > 0, age between 1-120 years) for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What's new in the CKD-EPI 2021 equation?
A: The 2021 version features updated coefficients (142, -1.200, 0.9938) and refined gender adjustments based on larger, more diverse population studies.

Q2: How does this differ from previous CKD-EPI equations?
A: The 2021 equation provides improved accuracy across all GFR ranges and better performance in diverse ethnic populations compared to earlier versions.

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

Q4: Are there population limitations?
A: While improved, the equation may still have limitations in extremes of age, body composition, and certain ethnic groups not well represented in validation studies.

Q5: When should confirmatory testing be considered?
A: Consider measured GFR tests when eGFR results are inconsistent with clinical presentation or when precise drug dosing is required in high-risk patients.