GFR Calculator Without Cystatin C

CKD-EPI 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 the GFR Calculator Without Cystatin C?

The GFR Calculator Without Cystatin C estimates glomerular filtration rate (GFR) using the CKD-EPI equation based solely on serum creatinine, age, and gender. This calculator provides an accurate assessment of kidney function without requiring cystatin C measurements.

2. How Does the Calculator Work?

The calculator uses the CKD-EPI 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 equation provides a refined estimate of kidney function using serum creatinine as the primary biomarker, with adjustments for age and gender differences in muscle mass and creatinine production.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for detecting chronic kidney disease, monitoring disease progression, determining appropriate medication dosages, and assessing overall kidney health.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Ensure all values are valid (creatinine > 0, age between 1-120 years). Use fasting serum creatinine values for optimal accuracy.

5. Frequently Asked Questions (FAQ)

Q1: Why use this equation instead of other GFR formulas?
A: This CKD-EPI creatinine-based equation provides excellent accuracy across a wide range of GFR values and is widely validated in diverse populations.

Q2: What are the advantages of not using cystatin C?
A: Eliminates the need for additional laboratory testing, reduces costs, and provides results using commonly available serum creatinine measurements.

Q3: When should serum creatinine be measured?
A: Morning fasting samples are preferred, but random samples are acceptable. Avoid testing immediately after high-protein meals or intense physical activity.

Q4: Are there limitations to this equation?
A: May be less accurate in individuals with extreme muscle mass, amputees, pregnant women, or those with rapidly changing kidney function.

Q5: Can this calculator be used for medication dosing?
A: While useful for screening and monitoring, for precise drug dosing in critical situations, measured GFR or combined creatinine-cystatin C equations may be preferred.