Mayo Clinic GFR Calculator

Mayo Clinic Quadratic Equation:

\[ eGFR = \exp(1.911 + \frac{5.249}{Scr} - \frac{2.114}{Scr^2} - 0.00686 \times Age - (0.205 \text{ if female})) \]

Estimated GFR (eGFR):

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1. What is the Mayo Clinic Quadratic Equation?

The Mayo Clinic Quadratic Equation is an alternative method for estimating glomerular filtration rate (GFR) from serum creatinine, age, and sex. It was developed to provide accurate GFR estimation across a wide range of kidney function levels.

2. How Does the Calculator Work?

The calculator uses the Mayo Clinic Quadratic equation:

\[ eGFR = \exp(1.911 + \frac{5.249}{Scr} - \frac{2.114}{Scr^2} - 0.00686 \times Age - (0.205 \text{ if female})) \]

Where:

\( Scr \) — Serum creatinine (mg/dL), use 0.8 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 equation uses 0.8 mg/dL for calculation to improve accuracy at higher GFR levels.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for detecting kidney disease, monitoring disease progression, and adjusting medication dosages based on kidney function.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. The calculator automatically applies the 0.8 mg/dL minimum for creatinine values below this threshold.

5. Frequently Asked Questions (FAQ)

Q1: Why use the Mayo Clinic Quadratic Equation?
A: This equation provides good accuracy across the spectrum of kidney function and is particularly useful in populations with preserved or mildly reduced kidney function.

Q2: What is the significance of the 0.8 mg/dL rule?
A: This rule prevents overestimation of GFR at very low creatinine levels and improves the equation's performance in individuals with normal or supranormal kidney function.

Q3: How does this compare to CKD-EPI and MDRD equations?
A: The Mayo Clinic equation may provide better accuracy in certain populations, especially those with GFR > 60 mL/min/1.73m², though CKD-EPI is more widely used currently.

Q4: Are there limitations to this equation?
A: Like other creatinine-based equations, it may be less accurate in extremes of age, body composition, or in populations with rapidly changing kidney function.

Q5: When was this equation developed and validated?
A: The Mayo Clinic Quadratic Equation was developed and validated in the early 2000s using data from the Mayo Clinic patient population.