U Kidney 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):

Unit Converter ▲

Unit Converter ▼

From:	To:

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 a power function relationship between creatinine and GFR, with demographic adjustments for gender and race.

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. Ensure all values are 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 eGFR categories for CKD staging?
A: G1: ≥90, G2: 60-89, G3a: 45-59, G3b: 30-44, G4: 15-29, G5: <15 mL/min/1.73m².

Q3: When is the best time to measure serum creatinine?
A: Fasting morning samples are preferred, but random samples are acceptable. Avoid testing after high-protein meals or intense physical activity.

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

Q5: Can this calculator be used for medication dosing?
A: While useful for screening, for precise drug dosing in critical situations, measured GFR methods are recommended.