Normal GFR Calculation

Normal GFR 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 Normal GFR Calculation?

The Normal GFR calculation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This equation is specifically designed to assess normal kidney function ranges and provides accurate estimation for individuals with preserved renal function.

2. How Does The Calculator Work?

The calculator uses the Normal GFR 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 optimized estimation for normal kidney function ranges, with coefficients specifically calibrated for accurate GFR assessment in healthy individuals.

3. Importance Of Normal GFR Assessment

Details: Assessing normal GFR ranges is essential for early detection of kidney function changes, monitoring healthy individuals, and establishing baseline kidney function for comparison over time.

4. Using The Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Normal GFR is typically >90 mL/min/1.73m². All values must be valid (creatinine > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: What Is Considered A Normal GFR Value?
A: Normal GFR is generally ≥90 mL/min/1.73m². Values between 60-89 may indicate mildly reduced kidney function and should be monitored.

Q2: How Does Age Affect Normal GFR?
A: GFR naturally declines with age. A GFR of 70-80 mL/min/1.73m² may be normal for an 80-year-old but concerning for a 30-year-old.

Q3: When Should I Get My GFR Checked?
A: Regular GFR assessment is recommended for individuals with risk factors like hypertension, diabetes, family history of kidney disease, or those over 60 years old.

Q4: Can GFR Values Fluctuate?
A: Yes, GFR can vary due to hydration status, diet, exercise, and temporary health conditions. Persistent abnormalities require medical evaluation.

Q5: What If My GFR Is Below Normal?
A: Consult a healthcare provider for comprehensive evaluation. Additional tests may be needed to determine the cause and appropriate management.