GFR Calculation CKD EPI

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 Equation?

The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. It provides an accurate assessment of kidney function and is widely used in clinical practice.

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 different demographic groups.

3. Importance of GFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, and guiding medication dosing decisions in clinical practice.

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).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between this and other CKD-EPI equations?
A: This version uses specific coefficients (142, -1.200, 0.9938) optimized for accurate GFR estimation across different populations.

Q2: What are normal eGFR values?
A: Normal GFR is generally ≥90 mL/min/1.73m², though values naturally decline with advancing age.

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 intense physical activity.

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

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