eGFR Calculator Kidney.Org

Kidney.org eGFR 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 Kidney.org eGFR Equation?

The Kidney.org eGFR equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This equation provides a standardized method for assessing kidney function and is widely used in clinical practice.

2. How Does the Calculator Work?

The calculator uses the Kidney.org eGFR 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:

\( eGFR \) — Estimated glomerular filtration rate (mL/min/1.73m²)
\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male, unitless)
\( \alpha \) — -0.241 (female) or -0.302 (male, unitless)
\( age \) — 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.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, monitoring kidney function over time, and guiding appropriate medication dosing for renal clearance.

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). Use fasting serum creatinine values for most accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What makes this equation different from CKD-EPI?
A: This Kidney.org equation uses slightly different coefficients (142 vs 141, different alpha values) and is optimized for specific clinical applications.

Q2: What are the clinical ranges for eGFR?
A: Normal eGFR is ≥90 mL/min/1.73m². Stage 1 CKD: ≥90 with kidney damage; Stage 2: 60-89; Stage 3: 30-59; Stage 4: 15-29; Stage 5: <15 or dialysis.

Q3: When is the best time to measure creatinine?
A: Morning fasting samples are preferred. Avoid testing after high-protein meals, intense exercise, or dehydration as these can temporarily elevate creatinine levels.

Q4: What populations may have inaccurate results?
A: This equation may be less accurate in extremes of age, amputees, pregnant women, severe malnutrition, obesity, and those with rapidly changing kidney function.

Q5: How often should eGFR be monitored?
A: Frequency depends on clinical context: annually for screening, more frequently (every 3-6 months) for known CKD patients, and as needed for medication adjustments.