GFR Calculator AA

CKD-EPI Equation:

\[ eGFR = 141 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.209} \times 0.993^{age} \times (1.018 \text{ if female}) \times 1.159 \]

Estimated GFR (eGFR):

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1. What is the CKD-EPI Creatinine Equation?

The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, sex, and race. This calculator specifically uses the African American version with the race factor of 1.159 for more accurate GFR estimation in this population.

2. How Does the Calculator Work?

The calculator uses the CKD-EPI equation for African American population:

\[ eGFR = 141 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.209} \times 0.993^{age} \times (1.018 \text{ if female}) \times 1.159 \]

Where:

\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male)
\( \alpha \) — -0.329 (female) or -0.411 (male)
\( age \) — Age in years
1.018 — Female multiplier
1.159 — African American race multiplier

Explanation: This equation accounts for the non-linear relationship between creatinine and GFR, with specific coefficients optimized for African American individuals.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease in African American populations, determining disease stage, and guiding appropriate treatment and medication dosing.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. This calculator is specifically designed for African American individuals with the fixed race factor of 1.159.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a specific calculator for African American individuals?
A: African American individuals typically have higher muscle mass and creatinine production, requiring a race-specific multiplier (1.159) for accurate GFR estimation.

Q2: What are normal eGFR values for African American individuals?
A: Normal is generally ≥90 mL/min/1.73m², though values decline with age. Below 60 for 3+ months indicates CKD.

Q3: When should creatinine be measured?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise.

Q4: Are there limitations to this equation?
A: Less accurate in extremes of age/weight, amputees, pregnant women, and those with rapidly changing kidney function.

Q5: Should this be used for drug dosing?
A: For precise drug dosing, measured GFR (e.g., via iohexol clearance) may be needed in certain populations.