National Kidney Foundation MDRD GFR Calculator

MDRD Equation:

\[ eGFR = 175 \times Scr^{-1.154} \times Age^{-0.203} \times (0.742 \text{ if female}) \times (1.212 \text{ if Black}) \]

Serum Creatinine (Scr):

mg/dL

Age:

years

Gender:

Race:

Estimated GFR (eGFR):

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1. What is the MDRD GFR Equation?

The MDRD (Modification of Diet in Renal Disease) equation estimates glomerular filtration rate (GFR) from serum creatinine, age, sex, and race. It was developed by the National Kidney Foundation and has been widely used for assessing kidney function in clinical practice.

2. How Does the Calculator Work?

The calculator uses the MDRD equation:

\[ eGFR = 175 \times Scr^{-1.154} \times Age^{-0.203} \times (0.742 \text{ if female}) \times (1.212 \text{ if Black}) \]

Where:

\( Scr \) — Serum creatinine (mg/dL)
\( Age \) — Age in years
0.742 — Female multiplier
1.212 — Black race multiplier

Explanation: The equation uses a power function to model the inverse relationship between serum creatinine and GFR, with adjustments for age, gender, and race.

3. Importance of eGFR Calculation

Details: The MDRD equation provides a standardized method for estimating kidney function, helping in the diagnosis and staging of chronic kidney disease, and guiding treatment decisions.

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). The calculator provides eGFR in mL/min/1.73m².

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between MDRD and CKD-EPI equations?
A: MDRD is more accurate at lower GFR levels (<60 mL/min/1.73m²), while CKD-EPI performs better at higher GFR levels and is less likely to misclassify individuals with normal or mildly reduced kidney function.

Q2: What are the limitations of the MDRD equation?
A: The equation may be less accurate in elderly patients, those with extreme body sizes, pregnant women, and populations with different muscle mass than the original study cohort.

Q3: When was the MDRD equation developed?
A: The MDRD equation was developed in 1999 based on data from the Modification of Diet in Renal Disease study.

Q4: Is the MDRD equation still used today?
A: While CKD-EPI is now preferred for general use, MDRD remains valuable for specific clinical scenarios and is still widely used in many healthcare settings.

Q5: How does race affect the calculation?
A: The race multiplier accounts for observed differences in muscle mass and creatinine generation rates between Black and non-Black populations.