GFR Calculator MedCalc

MedCalc GFR using CKD-EPI:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Estimated GFR (eGFR):

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1. What is the MedCalc GFR Calculator?

The MedCalc GFR Calculator uses a modified CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, and sex. This version provides optimized coefficients for enhanced accuracy in clinical practice.

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 uses refined coefficients (142, -1.200, 0.9938, 1.012) to provide improved GFR estimation accuracy across different patient populations.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, monitoring disease progression, determining appropriate medication dosages, and assessing overall kidney health.

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). Use fasting serum creatinine values for optimal accuracy.

5. Frequently Asked Questions (FAQ)

Q1: How does MedCalc version differ from standard CKD-EPI?
A: The MedCalc version uses optimized coefficients (142 instead of 141, -1.200 instead of -1.209, 0.9938 instead of 0.993, and 1.012 instead of 1.018 for females) for enhanced precision.

Q2: What are the clinical applications of this calculator?
A: This calculator is used for screening, diagnosis, and monitoring of chronic kidney disease, as well as for drug dosing adjustments in patients with renal impairment.

Q3: When is the best time to measure serum 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: Are there patient populations where this equation may be less accurate?
A: Accuracy may be reduced in extremes of age (<18 or >80 years), extremes of body size, amputees, pregnant women, and patients with rapidly changing kidney function.

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