1. What is the Mayo Clinic Quadratic eGFR Equation?

The Mayo Clinic Quadratic equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This equation was developed to provide accurate GFR estimation across a wide range of kidney function levels, with special consideration for low creatinine values.

2. How Does the Calculator Work?

The calculator uses the Mayo Clinic Quadratic equation:

Where:

• \( Scr \) — Serum creatinine (mg/dL), using 0.8 mg/dL if Scr < 0.8 mg/dL
• \( Age \) — Age in years
• 0.205 — Female adjustment factor

Special Rule: If serum creatinine is less than 0.8 mg/dL, the calculator automatically uses 0.8 mg/dL in the calculation to prevent overestimation of GFR.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, monitoring disease progression, and guiding appropriate medication dosing based on renal function.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Note that creatinine values below 0.8 mg/dL will be automatically adjusted to 0.8 mg/dL as per the Mayo Clinic equation specifications.

5. Frequently Asked Questions (FAQ)

Q1: Why does the Mayo Clinic equation use Scr=0.8 for low creatinine values?
A: This adjustment prevents overestimation of GFR in individuals with very low serum creatinine levels, which can occur in patients with low muscle mass or malnutrition.

Q2: How does the Mayo Clinic equation compare to CKD-EPI?
A: The Mayo Clinic Quadratic equation may provide better accuracy in certain populations, particularly those with very high or very low GFR values, though CKD-EPI is more widely used.

Q3: What are the limitations of this equation?
A: Like all creatinine-based equations, it may be less accurate in extremes of age, body composition, amputees, pregnant women, and those with rapidly changing kidney function.

Q4: When is this equation particularly useful?
A: It can be valuable in populations where traditional equations may overestimate GFR, such as elderly patients or those with low muscle mass.

Q5: Should this equation be used for drug dosing decisions?
A: For critical drug dosing decisions, especially with narrow therapeutic windows, measured GFR may be preferred over estimated GFR.