Calculate Estimated Creatinine Clearance

Cockcroft-Gault Equation:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Estimated Creatinine Clearance (eCrCl):

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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 for assessing kidney function.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

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

Where:

\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( SCr \) — Serum creatinine in mg/dL
\( 0.85 \) — Female gender adjustment factor
\( 72 \) — Constant factor

Explanation: The equation estimates creatinine clearance based on the premise that creatinine production is proportional to muscle mass, which decreases with age and differs between genders.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance estimation is essential for drug dosing adjustments, particularly for medications with narrow therapeutic windows that are primarily excreted by the kidneys. It also helps in assessing renal function and monitoring kidney disease progression.

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 eGFR and eCrCl?
A: eGFR estimates glomerular filtration rate standardized to body surface area, while eCrCl estimates actual creatinine clearance and is often preferred for drug dosing calculations.

Q2: What are normal creatinine clearance values?
A: Normal values are approximately 95-125 mL/min for men and 85-115 mL/min for women, decreasing with age.

Q3: When should ideal body weight be used instead of actual weight?
A: For obese patients (BMI > 30), ideal body weight is often recommended to avoid overestimating renal function.

Q4: Are there limitations to the Cockcroft-Gault equation?
A: It may be less accurate in elderly patients, those with extreme body weights, malnutrition, amputees, or rapidly changing renal function.

Q5: Why is this equation still used despite newer equations?
A: Many drug dosing guidelines and clinical trials were based on Cockcroft-Gault, making it the preferred method for medication adjustment decisions.