U Kidney eGFR 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 factors to estimate kidney function, with different coefficients for different demographic groups.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for diagnosing chronic kidney disease, determining disease stage, monitoring disease progression, and guiding appropriate 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 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 normal eGFR ranges?
A: Normal eGFR is generally ≥90 mL/min/1.73m². Values between 60-89 may indicate early kidney disease, while values below 60 for 3+ months indicate chronic kidney disease.

Q3: When is the best time to measure serum creatinine?
A: Morning fasting samples are preferred, but random samples are acceptable. Avoid testing shortly after meat consumption or strenuous exercise.

Q4: What are the limitations of the MDRD equation?
A: The equation may be less accurate in elderly patients, those with extreme body sizes, amputees, pregnant women, and individuals with rapidly changing kidney function.

Q5: Can this calculator be used for medication dosing?
A: While useful for estimating kidney function, for precise medication dosing in critical situations, measured GFR methods may be required.