eGFR 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 eGFR Calculator?

The eGFR 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 for 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 CKD-EPI 2021 equation incorporates updated coefficients and exponents to provide more accurate GFR estimation, particularly in populations with normal or mildly reduced kidney function.

3. Importance of eGFR Calculation

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

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 instead of 141), modified exponents (-1.200 instead of -1.209), and refined gender factors (1.012 instead of 1.018) for improved accuracy.

Q2: What are the clinical implications of eGFR values?
A: Normal eGFR is ≥90 mL/min/1.73m². Values between 60-89 may indicate mild reduction, while values below 60 for 3+ months suggest chronic kidney disease requiring further evaluation.

Q3: When is the best time to measure serum creatinine?
A: Morning fasting samples are preferred, but random samples are acceptable. Avoid testing shortly after high-protein meals or intense physical activity.

Q4: What populations may have limited accuracy with this equation?
A: The equation may be less accurate in extreme age groups, pregnant women, individuals with amputations, severe malnutrition, or rapidly changing kidney function.

Q5: Can this calculator be used for medication dosing?
A: While useful for screening, precise drug dosing in critical situations may require measured GFR methods for optimal accuracy and safety.