Kidney Function GFR Calculator

Kidney Function 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 the Kidney Function GFR Equation?

The Kidney Function GFR equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This specialized equation provides accurate assessment of kidney function for clinical evaluation and monitoring.

2. How Does the Calculator Work?

The calculator uses the Kidney Function 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: The equation accounts for non-linear relationship between creatinine and GFR, with gender-specific coefficients optimized for kidney function assessment.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for evaluating kidney health, detecting early renal impairment, and guiding clinical decisions regarding medication adjustments and treatment planning.

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 years). Use fasting serum creatinine values for optimal accuracy.

5. Frequently Asked Questions (FAQ)

Q1: What makes this equation different from others?
A: This equation uses specific coefficients (142, -1.200, 0.9938) optimized for kidney function assessment across diverse populations.

Q2: What are normal eGFR values?
A: Normal GFR is generally ≥90 mL/min/1.73m². Values between 60-89 may indicate mild reduction, while values below 60 for 3+ months suggest chronic kidney disease.

Q3: When is the best time to measure creatinine?
A: Morning fasting samples are preferred. Avoid testing after high-protein meals, intense exercise, or dehydration for accurate results.

Q4: Are there limitations to this equation?
A: Accuracy may be reduced in elderly patients, those with extreme body composition, muscle wasting, or rapidly changing renal function.

Q5: Can this be used for medication dosing?
A: While useful for screening, critical medication dosing decisions should consider multiple factors including measured GFR when available.