What Is 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 GFR Calculation?

GFR (Glomerular Filtration Rate) calculation estimates how well your kidneys are filtering waste from your blood. The CKD-EPI equation provides a standardized method to estimate GFR using serum creatinine levels and demographic factors.

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:

\( eGFR \) — Estimated Glomerular Filtration Rate (mL/min/1.73m²)
\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male, unitless)
\( \alpha \) — -0.241 (female) or -0.302 (male, unitless)
\( age \) — Age in years
1.012 — Female multiplier

Explanation: This equation calculates GFR based on serum creatinine levels adjusted for age and gender, providing a more accurate assessment of kidney function.

3. Importance Of eGFR Calculation

Details: GFR calculation is essential for detecting kidney disease early, monitoring kidney function over time, and guiding treatment decisions for patients with renal impairment.

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) for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What Is The Difference Between GFR And eGFR?
A: GFR is the actual glomerular filtration rate measured through clearance tests, while eGFR is an estimated value calculated using equations like CKD-EPI based on serum creatinine and other factors.

Q2: Why Is Age A Factor In GFR Calculation?
A: Kidney function naturally declines with age, so the equation includes an age adjustment factor (0.9938^Age) to account for this physiological change.

Q3: What Are The Normal eGFR Ranges?
A: Normal eGFR is typically ≥90 mL/min/1.73m². Values between 60-89 may indicate mild kidney disease, while values below 60 for 3+ months suggest chronic kidney disease.

Q4: How Often Should GFR Be Calculated?
A: Frequency depends on individual risk factors, but generally annually for high-risk patients and every 1-2 years for those with stable kidney function.

Q5: Can Medications Affect GFR Calculations?
A: Yes, certain medications can affect creatinine levels and therefore eGFR results. Always inform your healthcare provider about all medications you're taking.