eGFR Calculation Formula

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 eGFR Calculation Formula?

The eGFR (estimated Glomerular Filtration Rate) Calculation Formula uses the CKD-EPI 2021 equation to estimate kidney function from serum creatinine, age, and sex. This updated version provides improved accuracy in assessing kidney function across different 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: This equation incorporates updated coefficients for improved accuracy in estimating glomerular filtration rate based on serum creatinine levels and demographic factors.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for detecting early kidney disease, monitoring kidney function over time, and making informed clinical decisions about medication dosing and treatment plans.

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 includes updated coefficients (142, -1.200, 0.9938) and gender-specific parameters for improved accuracy across diverse populations.

Q2: How does this differ from previous versions?
A: This version provides better precision, especially in individuals with normal or near-normal kidney function, and has been validated in larger, more diverse populations.

Q3: What are the clinical applications of eGFR?
A: eGFR is used for CKD screening, staging kidney disease, monitoring disease progression, and adjusting drug dosages for medications cleared by the kidneys.

Q4: Are there limitations to this equation?
A: The equation may be less accurate in extremes of age, body composition, certain ethnic groups, and individuals with rapidly changing kidney function or unusual muscle mass.

Q5: When should eGFR be interpreted with caution?
A: Use caution in pregnant women, severely malnourished individuals, amputees, and those with skeletal muscle disorders or rapidly changing creatinine levels.