Med Calc Creatinine Clearance Calculator

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 is a widely used formula 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 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 equation estimates creatinine clearance based on age, weight, serum creatinine, and gender, providing an approximation of kidney function.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance estimation is essential for drug dosing adjustments, assessing renal function, and monitoring patients with kidney disease. Many medications require dose modifications based on CrCl values.

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 using the Cockcroft-Gault equation, while eGFR estimates glomerular filtration rate using equations like CKD-EPI or MDRD. They serve similar purposes but use different calculations.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for men and 85-115 mL/min for women. Values decline with age.

Q3: When is ideal body weight used instead of actual weight?
A: For obese patients (BMI > 30), some guidelines recommend using ideal body weight rather than actual weight in the calculation.

Q4: What are the limitations of the Cockcroft-Gault equation?
A: Less accurate in elderly patients, those with extreme body weights, muscle wasting conditions, and when serum creatinine is not at steady state.

Q5: Is this equation suitable for all populations?
A: The equation was derived primarily from Caucasian populations and may be less accurate in other ethnic groups. It's also not validated in children.