National Kidney Foundation GFR Calculation

National Kidney Foundation 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 National Kidney Foundation GFR Equation?

The National Kidney Foundation GFR equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This 2021 updated equation provides enhanced accuracy for kidney function assessment across diverse populations.

2. How Does the Calculator Work?

The calculator uses the National Kidney Foundation 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 incorporates updated coefficients and exponents to provide more precise GFR estimation, particularly in populations with preserved kidney function.

3. Importance of GFR Calculation

Details: Accurate GFR estimation is essential for early detection of kidney disease, monitoring disease progression, and guiding appropriate clinical management and treatment decisions.

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).

5. Frequently Asked Questions (FAQ)

Q1: What makes this equation different from CKD-EPI?
A: This 2021 equation uses updated coefficients (142, -1.200, 0.9938) and refined gender adjustments for improved accuracy across different age groups.

Q2: What are the clinical applications of this calculation?
A: Used for screening, diagnosis, and staging of chronic kidney disease, as well as for medication dosing adjustments in patients with renal impairment.

Q3: How does age affect GFR calculation?
A: GFR naturally declines with age due to physiological changes in kidney structure and function, which is accounted for in the age exponent (0.9938).

Q4: Are there population limitations for this equation?
A: While validated across diverse populations, caution is advised in extremes of body composition, amputees, and patients with rapidly changing kidney function.

Q5: How frequently should GFR be monitored?
A: Frequency depends on clinical context - annually for screening, more frequently for known kidney disease or when monitoring response to treatment.