American Kidney Association GFR Calculator

American Kidney Fund GFR 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 American Kidney Fund GFR Equation?

The American Kidney Fund GFR equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This equation provides an accurate assessment of kidney function and is widely used in clinical practice for evaluating renal health.

2. How Does the Calculator Work?

The calculator uses the American Kidney Fund GFR 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 different coefficients for different demographic groups to provide accurate kidney function estimation.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, determining disease stage, monitoring disease progression, and guiding appropriate medication dosing for patients with renal impairment.

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). For most accurate results, use fasting serum creatinine levels.

5. Frequently Asked Questions (FAQ)

Q1: What makes this equation different from others?
A: The American Kidney Fund GFR equation uses specific coefficients optimized for accurate kidney function estimation across diverse populations.

Q2: What are normal eGFR values?
A: Normal eGFR is generally ≥90 mL/min/1.73m². Values between 60-89 may indicate mild kidney impairment, 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 after high-protein meals or strenuous physical activity.

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

Q5: Can this calculator be used for medication dosing?
A: While useful for screening, for precise drug dosing in patients with kidney impairment, consult healthcare providers who may use more specific methods.