How Do You Calculate an eGFR

CKD-EPI 2021 Creatinine Equation Calculator

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):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the CKD-EPI 2021 Creatinine Equation?

The CKD-EPI 2021 (Chronic Kidney Disease Epidemiology Collaboration) equation is an updated version that estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This newer equation provides improved accuracy and removes race as a variable for more equitable assessment of kidney function.

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: The equation accounts for non-linear relationship between creatinine and GFR, with updated coefficients based on the latest research and without race adjustment.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, monitoring progression, and guiding medication dosing decisions.

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). The calculator uses the latest CKD-EPI 2021 equation without race adjustment.

5. Frequently Asked Questions (FAQ)

Q1: What's new in CKD-EPI 2021 compared to previous versions?
A: The 2021 version removes race as a variable and uses updated coefficients based on more diverse population data for improved equity and accuracy.

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

Q3: Why was race removed from the equation?
A: Race was removed to provide more equitable kidney function assessment and because race is a social construct rather than a biological variable.

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

Q5: When should creatinine be measured for accurate results?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise.