MedCalc GFR Calculator

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 MedCalc GFR Calculator?

The MedCalc GFR Calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, and sex. This implementation provides a specialized version of the CKD-EPI equation optimized for clinical use.

2. How Does the Calculator Work?

The calculator uses the MedCalc 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: This equation provides a refined estimation of kidney function using optimized coefficients for different demographic groups.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, monitoring disease progression, and determining appropriate medication dosages based on renal function.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Ensure all values are valid (creatinine > 0, age between 1-120 years).

5. Frequently Asked Questions (FAQ)

Q1: What makes the MedCalc version different?
A: The MedCalc version uses slightly different coefficients (142, -1.200, 0.9938, 1.012) optimized for clinical accuracy.

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: This equation may be less accurate in elderly patients, those with extreme body weights, amputees, pregnant women, and individuals with rapidly changing kidney function.

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