Calculation of GFR from Serum Creatinine

GFR from Serum Creatinine 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 GFR from Serum Creatinine?

This equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. It provides an accurate assessment of kidney function based on creatinine levels and demographic factors.

2. How Does the Calculator Work?

The calculator uses the GFR from Serum Creatinine 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 the non-linear relationship between creatinine and GFR, with different coefficients for males and females.

3. Importance of GFR Calculation

Details: Accurate GFR estimation is essential for diagnosing kidney disease, monitoring kidney function, and guiding appropriate medical treatment and medication dosing.

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).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between this equation and CKD-EPI?
A: This equation uses different coefficients (142 vs 141, -1.200 vs -1.209, 0.9938 vs 0.993) and does not include race adjustment.

Q2: What are normal GFR values?
A: Normal GFR is generally ≥90 mL/min/1.73m², though values naturally decline with advancing age.

Q3: When is the best time to measure creatinine?
A: Morning fasting samples are preferred, but random samples can be used. Avoid testing after high-protein meals or intense physical activity.

Q4: Are there limitations to this equation?
A: The equation may be less accurate in elderly patients, those with extreme body weights, amputees, pregnant women, and individuals with rapidly changing kidney function.

Q5: Can this be used for medication dosing?
A: While useful for estimating kidney function, precise drug dosing may require measured GFR in specific clinical situations.