DaVita GFR Creatinine Clearance Calculator MDCalc

Cockcroft-Gault & MDRD Equations:

Cockcroft-Gault:
\[ CrCl = \frac{(140 - age) \times weight \times (0.85 \text{ if female})}{72 \times Scr} \]

MDRD:
\[ eGFR = 175 \times (Scr)^{-1.154} \times (age)^{-0.203} \times (0.742 \text{ if female}) \times (1.212 \text{ if black}) \]

Select Equation:

Serum Creatinine (Scr):

mg/dL

Age:

years

Gender:

Weight:

Race:

Result:

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1. What are Cockcroft-Gault and MDRD Equations?

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) which correlates with glomerular filtration rate (GFR), while the MDRD (Modification of Diet in Renal Disease) equation estimates GFR directly. Both are used to assess kidney function but have different applications and limitations.

2. How Do These Calculators Work?

Cockcroft-Gault equation:

\[ CrCl = \frac{(140 - age) \times weight \times (0.85 \text{ if female})}{72 \times Scr} \]

MDRD equation:

\[ eGFR = 175 \times (Scr)^{-1.154} \times (age)^{-0.203} \times (0.742 \text{ if female}) \times (1.212 \text{ if black}) \]

Key differences:

Cockcroft-Gault requires weight and estimates CrCl in mL/min
MDRD doesn't require weight and estimates GFR standardized to 1.73m² body surface area
Cockcroft-Gault is often used for drug dosing, while MDRD is used for CKD staging

3. Importance of Creatinine Clearance Calculation

Details: Accurate estimation of kidney function is essential for drug dosing (especially nephrotoxic medications), assessing renal impairment, and monitoring kidney disease progression.

4. Using the Calculator

Tips:

For Cockcroft-Gault: Enter weight in kg, serum creatinine in mg/dL, age in years
For MDRD: Enter serum creatinine in mg/dL, age in years, select gender and race
All values must be valid (creatinine > 0, age between 1-120, weight > 0 if using Cockcroft-Gault)

5. Frequently Asked Questions (FAQ)

Q1: Which equation should I use?
A: Cockcroft-Gault is preferred for drug dosing, while MDRD is better for CKD staging. Clinical context matters.

Q2: Why does MDRD not need weight?
A: MDRD reports GFR standardized to 1.73m² body surface area, while Cockcroft-Gault reports actual CrCl.

Q3: Are these equations accurate for all patients?
A: No - both have reduced accuracy in extremes of age/weight, amputees, and those with unstable creatinine.

Q4: How often should creatinine clearance be measured?
A: Frequency depends on clinical situation - for stable CKD patients, every 3-12 months may be sufficient.

Q5: What about the CKD-EPI equation?
A: CKD-EPI is generally more accurate than MDRD, especially at higher GFRs, but MDRD is still widely used.