American Kidney Foundation GFR Calculator

American Kidney Foundation GFR Calculator using CKD-EPI 2021:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Estimated GFR (eGFR):

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1. What is the American Kidney Foundation GFR Calculator?

The American Kidney Foundation GFR Calculator uses the CKD-EPI 2021 equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, and sex. This updated equation provides enhanced accuracy for assessing kidney function across diverse populations.

2. How Does the Calculator Work?

The calculator uses the American Kidney Foundation 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 based on recent research to improve GFR estimation accuracy, particularly in specific demographic groups.

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 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).

5. Frequently Asked Questions (FAQ)

Q1: What makes the 2021 equation different from previous versions?
A: The 2021 equation includes updated coefficients and refined parameters based on larger, more diverse population studies for improved accuracy.

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

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

Q4: Are there limitations to this equation?
A: The equation may be less accurate in extreme age groups, pregnant women, individuals with amputations, or those with rapidly changing kidney function.

Q5: Can this calculator be used for medication dosing?
A: While useful for screening, precise drug dosing may require measured GFR in certain clinical situations or specific patient populations.