What is Calculated GFR

CKD-EPI 2021 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 Calculated GFR?

Calculated GFR (glomerular filtration rate) estimates kidney function using the CKD-EPI 2021 equation based on serum creatinine, age, and sex. It provides an accurate assessment of how well your kidneys are filtering waste from your blood.

2. How Does the Calculator Work?

The calculator uses the CKD-EPI 2021 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 updated 2021 equation provides improved accuracy in GFR estimation across different populations and creatinine ranges.

3. Importance of GFR Calculation

Details: GFR calculation is essential for detecting early kidney disease, monitoring kidney function over time, and guiding treatment decisions for various medical conditions.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Ensure creatinine values are from recent blood tests and age is accurate for precise results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CKD-EPI 2009 and 2021 equations?
A: The 2021 equation uses updated coefficients (142 instead of 141, different exponents) and removes race adjustment for improved equity and accuracy.

Q2: What do different GFR ranges indicate?
A: ≥90 (normal), 60-89 (mild reduction), 30-59 (moderate reduction), 15-29 (severe reduction), <15 (kidney failure).

Q3: How often should GFR be calculated?
A: For people with risk factors (diabetes, hypertension), annual testing is recommended. More frequent monitoring if kidney disease is present.

Q4: Can diet affect creatinine levels?
A: Yes, high protein intake and creatine supplements can temporarily increase creatinine levels, affecting GFR calculations.

Q5: When is measured GFR preferred over calculated GFR?
A: Measured GFR (using clearance methods) is preferred in extreme body sizes, rapidly changing kidney function, or when precise dosing of toxic drugs is needed.