CKD EPI 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 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 kidney function, with different coefficients for different demographic groups.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, monitoring progression, and guiding medication dosing 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 years).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between MDRD and CKD-EPI?
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 normal eGFR values?
A: Normal eGFR is generally ≥90 mL/min/1.73m². Values below 60 mL/min/1.73m² for 3+ months indicate chronic kidney disease.

Q3: When is the best time to measure creatinine?
A: Morning fasting samples are ideal, but random samples are acceptable. Avoid testing after consuming large amounts of meat or following vigorous exercise.

Q4: What are the limitations of the MDRD equation?
A: Less accurate in extremes of age and body size, amputees, pregnant women, and patients with rapidly changing kidney function or unusual muscle mass.

Q5: Can MDRD be used for drug dosing?
A: While commonly used, for precise drug dosing in certain populations, measured GFR (e.g., via iohexol clearance) may be more appropriate.