eGFR Calculator Cockcroft Gault

Cockcroft-Gault Formula:

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

Age (years):

years

Weight (kg):

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 a surrogate 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 formula:

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

Where:

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

Explanation: The formula estimates creatinine clearance based on age, weight, serum creatinine, and gender, with a correction factor of 0.85 for females to account for typically lower muscle mass.

3. Importance of CrCl Calculation

Details: Creatinine clearance estimation is crucial for drug dosing adjustments, particularly for medications with narrow therapeutic windows that are primarily eliminated by the kidneys. It helps prevent drug toxicity in patients with impaired renal function.

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 (Cockcroft-Gault) and eGFR (MDRD/CKD-EPI) are both estimates of kidney function, but they use different formulas and may give different results. CrCl is often preferred for drug dosing.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 90-120 mL/min for young adults. Values decline with age, and below 60 mL/min may indicate renal impairment.

Q3: When should I use ideal body weight vs actual body weight?
A: For obese patients (BMI > 30), some guidelines recommend using ideal body weight rather than actual body weight in the Cockcroft-Gault formula.

Q4: Are there limitations to this formula?
A: The formula may overestimate CrCl in elderly patients, malnourished individuals, and those with unstable renal function. It's less accurate at extremes of age and body size.

Q5: Why is there a gender adjustment?
A: Females typically have lower muscle mass than males, resulting in lower creatinine production. The 0.85 multiplier accounts for this physiological difference.