CKD EPI GFR Calculation

CKD-EPI 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 CKD-EPI GFR Calculation?

The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This specific version provides an accurate assessment of kidney function using optimized coefficients for different demographic groups.

2. How Does the Calculator Work?

The calculator uses the CKD-EPI 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 non-linear relationship between creatinine and GFR, with different coefficients for males and females to improve accuracy across different populations.

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

5. Frequently Asked Questions (FAQ)

Q1: What makes this CKD-EPI version different?
A: This version uses specific coefficients (142, -1.200, 0.9938, 1.012) optimized for improved accuracy in GFR estimation across diverse populations.

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

Q3: When is the best time to measure creatinine?
A: Morning fasting samples are preferred to avoid dietary influences. Avoid testing after high-protein meals or intense physical activity.

Q4: Are there limitations to this equation?
A: The equation may be less accurate in extremes of age, body composition, amputees, pregnant women, and those with rapidly changing kidney function or muscle mass.

Q5: Can this calculator be used for children?
A: No, this equation is validated for adults only. Pediatric GFR estimation requires different equations accounting for body surface area and developmental changes.