Kidney Australia eGFR Calculator

CKD-EPI Equation:

\[ eGFR = 141 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.209} \times 0.993^{age} \times (1.018 \text{ if female}) \times (1.159 \text{ if black}) \]

Serum Creatinine (Scr):

mg/dL

Age:

years

Gender:

Race:

Estimated GFR (eGFR):

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1. What Is The Kidney Australia eGFR Calculator?

The Kidney Australia eGFR Calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, sex, and race. This calculator provides healthcare professionals with an accurate assessment of kidney function based on the latest epidemiological research.

2. How Does The Calculator Work?

The calculator uses the CKD-EPI equation:

\[ eGFR = 141 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.209} \times 0.993^{age} \times (1.018 \text{ if female}) \times (1.159 \text{ if black}) \]

Where:

\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male)
\( \alpha \) — -0.329 (female) or -0.411 (male)
\( age \) — Age in years
1.018 — Female multiplier
1.159 — Black race multiplier

Explanation: This equation accounts for the non-linear relationship between creatinine and GFR, with different coefficients optimized for different demographic groups to provide more accurate estimates across the full range of kidney function.

3. Importance Of eGFR Calculation

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

4. Using The Calculator

Tips: Enter serum creatinine in mg/dL, age in years, select gender and race. Ensure all values are valid (creatinine > 0, age between 1-120 years). For optimal accuracy, use recent laboratory results and consider patient's clinical context.

5. Frequently Asked Questions (FAQ)

Q1: Why Use CKD-EPI Instead Of MDRD?
A: The CKD-EPI equation is more accurate at higher GFR levels (>60 mL/min/1.73m²) and less likely to misclassify individuals with mildly reduced kidney function, providing better precision across the full spectrum of kidney function.

Q2: What Are Normal eGFR Values?
A: Normal eGFR is generally ≥90 mL/min/1.73m², though values naturally decline with age. A sustained eGFR below 60 mL/min/1.73m² for three months or more indicates chronic kidney disease.

Q3: When Should Creatinine Be Measured?
A: Morning fasting samples are ideal for consistency, though random samples are acceptable in clinical practice. Avoid testing shortly after meat-heavy meals or vigorous exercise, as these can temporarily elevate creatinine levels.

Q4: Are There Limitations To This Equation?
A: The equation may be less accurate in extremes of age and body composition, amputees, pregnant women, individuals with severe malnutrition or obesity, and those with rapidly changing kidney function.

Q5: Should This Be Used For Drug Dosing?
A: While useful for initial dosing estimates, for precise drug dosing in critical situations or specific populations, measured GFR (e.g., via iohexol or inulin clearance) may be required for optimal therapeutic management.