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 widely used before the development of the CKD-EPI equation and provides a reliable estimate of kidney function.

2. How Does the Calculator Work?

The calculator uses the MDRD equation:

Where:

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

Explanation: The equation provides an estimate of glomerular filtration rate based on serum creatinine levels adjusted for age, gender, and race.

3. Importance of eGFR Calculation

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

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).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between MDRD and CKD-EPI equations?
A: The MDRD equation is less accurate at higher GFR levels (>60 mL/min/1.73m²) compared to the CKD-EPI equation, which was developed to address this limitation.

Q2: What are normal eGFR values?
A: Normal is generally ≥90 mL/min/1.73m², though values decline with age. Below 60 for 3+ months indicates CKD.

Q3: When should creatinine be measured?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise.

Q4: Are there limitations to this equation?
A: Less accurate in extremes of age/weight, amputees, pregnant women, and those with rapidly changing kidney function.

Q5: Should this be used for drug dosing?
A: For precise drug dosing, measured GFR (e.g., via iohexol clearance) may be needed in certain populations.