GFR Calculator With Creatinine Test

GFR Formula Using Cr Test Result:

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

Serum Creatinine (Cr):

mg/dL

Age:

years

Gender:

Race:

Estimated GFR:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is GFR With Creatinine Test?

GFR (Glomerular Filtration Rate) estimation using creatinine test is a method to assess kidney function. It calculates how well your kidneys are filtering waste from your blood, using serum creatinine levels along with demographic factors.

2. How Does the Calculator Work?

The calculator uses the standard CKD-EPI equation:

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

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 — Black race multiplier

Explanation: The equation accounts for non-linear relationship between creatinine and GFR, with different coefficients for different demographic groups.

3. Importance of GFR Calculation

Details: GFR is the best overall index of kidney function. It helps diagnose kidney disease, monitor disease progression, and guide treatment decisions including medication dosing.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, select gender and race. All values must be valid (creatinine > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between GFR and eGFR?
A: GFR is the actual filtration rate, while eGFR is an estimate calculated from creatinine and other factors. True GFR requires more complex testing.

Q2: What are normal GFR values?
A: Normal is generally ≥90 mL/min/1.73m². Below 60 suggests kidney dysfunction, and below 15 typically requires dialysis.

Q3: How often should GFR be checked?
A: Frequency depends on risk factors. Annually for those at risk, more often if kidney disease is present or when monitoring treatment.

Q4: Can GFR be improved?
A: Some causes of reduced GFR are reversible. Controlling blood pressure, diabetes, and avoiding nephrotoxic drugs can help preserve kidney function.

Q5: Why does race affect GFR calculation?
A: Muscle mass and creatinine production vary by race. The adjustment factor accounts for these physiological differences in the estimation.