MDRD Calculator for GFR

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 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 to provide a more accurate assessment of kidney function in patients with chronic kidney disease.

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 serum creatinine, age, gender, and race to estimate glomerular filtration rate, which reflects kidney function.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing and staging chronic kidney disease, monitoring disease progression, and adjusting medication dosages for renal clearance.

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 years).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between MDRD and CKD-EPI equations?
A: MDRD is more accurate in patients with established CKD, 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 or dietary patterns.

Q3: When was the MDRD equation developed?
A: The MDRD equation was developed in 1999 and has been widely used for estimating GFR in clinical practice.

Q4: Can MDRD be used for all patient populations?
A: While useful for many patients, the equation may require validation or adjustment for specific ethnic groups or clinical situations not represented in the original study population.

Q5: How often should eGFR be monitored?
A: Frequency depends on clinical context - more frequently in patients with known kidney disease, diabetes, hypertension, or those taking nephrotoxic medications.