MD Calc for Creatinine Clearance

Cockcroft-Gault Formula:

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

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) from serum creatinine, age, weight, and gender. It helps assess kidney function and guide medication dosing, particularly for drugs that are renally eliminated.

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 gender adjustment factor
\( 72 \) — Constant factor

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

3. Importance of CrCl Calculation

Details: Creatinine clearance estimation is essential for drug dosing adjustments in patients with renal impairment, assessing kidney function, and monitoring renal 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 CrCl and eGFR?
A: CrCl estimates creatinine clearance using Cockcroft-Gault, while eGFR estimates glomerular filtration rate using equations like CKD-EPI. CrCl is often preferred 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 should ideal body weight be used?
A: For obese patients (BMI > 30), ideal body weight is often used instead of actual weight to avoid overestimating CrCl.

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

Q5: Can this be used for pediatric patients?
A: No, the Cockcroft-Gault formula is validated for adults only. Pediatric patients require age-specific formulas.