GFR Calculation CKD EPI Range

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 Equation?

The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This specific version provides accurate GFR estimation with normal range >90 mL/min/1.73m².

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: This equation provides a refined estimation of kidney function using updated coefficients for improved accuracy across different GFR ranges.

3. Importance of GFR Calculation

Details: Accurate GFR estimation is essential for assessing kidney function, diagnosing chronic kidney disease stages, and determining appropriate treatment plans. Normal GFR range is >90 mL/min/1.73m².

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). Results are expressed in mL/min/1.73m².

5. Frequently Asked Questions (FAQ)

Q1: What is the normal GFR range?
A: Normal GFR is generally >90 mL/min/1.73m². Values below 60 for 3+ months indicate chronic kidney disease.

Q2: How does this equation differ from other CKD-EPI versions?
A: This version uses specific coefficients (142, -1.200, 0.9938, 1.012) optimized for accurate GFR estimation across different populations.

Q3: Why are different coefficients used for males and females?
A: Muscle mass differences between genders affect creatinine production, requiring gender-specific coefficients for accurate GFR estimation.

Q4: When is the best time to measure creatinine?
A: Morning fasting samples are preferred, but random samples are acceptable. Avoid testing after high-protein meals or intense exercise.

Q5: Are there limitations to this calculation?
A: May be less accurate in extremes of age, body composition, amputees, pregnant women, and those with rapidly changing kidney function.