eGFR Calculator Cockcroft Gault Formula

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 Formula?

The Cockcroft-Gault formula is a widely used method for estimating creatinine clearance (CrCl), which serves as an approximation for glomerular filtration rate (GFR). It was developed in 1976 and remains commonly used for drug dosing adjustments in patients with renal impairment.

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 in mg/dL
\( 0.85 \) — Correction factor for female gender

Explanation: The formula estimates creatinine clearance based on age, weight, serum creatinine, and gender, providing a practical method for assessing renal function.

3. Importance of CrCl Calculation

Details: Creatinine clearance estimation is essential for appropriate drug dosing in patients with renal impairment, particularly for medications that are primarily eliminated by the kidneys and have narrow therapeutic windows.

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 higher than eGFR and is commonly used for drug dosing.

Q2: 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.

Q3: When is the Cockcroft-Gault formula most accurate?
A: It performs best in stable outpatients with normal muscle mass and stable renal function. It may overestimate CrCl in elderly, malnourished, or obese patients.

Q4: Are there limitations to this formula?
A: Limitations include inaccuracy in extremes of body weight, elderly patients, patients with changing renal function, and those with abnormal muscle mass.

Q5: Should ideal body weight be used instead of actual weight?
A: For obese patients (BMI > 30), some guidelines recommend using ideal body weight in the calculation to avoid overestimation of renal function.