GFR Calculator Cockcroft-Gault

Cockcroft-Gault Equation:

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

Age:

years

Weight:

Serum Creatinine (Scr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is the Cockcroft-Gault Equation?

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) from serum creatinine, age, weight, and gender. It is widely used for drug dosing adjustments in patients with renal impairment and provides an approximation of glomerular filtration rate (GFR).

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

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

Where:

\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( Scr \) — Serum creatinine (mg/dL)
0.85 — Female multiplier

Explanation: The equation estimates creatinine clearance based on demographic and laboratory parameters, with adjustment for gender differences in muscle mass and creatinine production.

3. Importance of CrCl Calculation

Details: Creatinine clearance estimation is essential for drug dosing adjustments in patients with renal impairment, assessing kidney function, and determining appropriate medication regimens for renally cleared drugs.

4. Using the Calculator

Tips: Enter age in years, weight in kilograms, serum creatinine in mg/dL, and select gender. All values must be valid (age between 1-120, weight > 0, creatinine > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CrCl and eGFR?
A: CrCl estimates creatinine clearance while eGFR estimates glomerular filtration rate. CrCl is often used for drug dosing, while eGFR is used for CKD staging.

Q2: When should ideal body weight be used?
A: For obese patients (BMI > 30), ideal body weight is often recommended instead of actual body weight for more accurate estimation.

Q3: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for young adults, decreasing with age. Values below 60 mL/min indicate renal impairment.

Q4: Are there limitations to this equation?
A: Less accurate in elderly, malnourished, obese patients, and those with unstable renal function or extreme muscle mass.

Q5: Can this be used for all medications?
A: While widely used, some medications may require more precise GFR measurement methods for accurate dosing.