Clinical Creatinine Clearance Calculator

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), which approximates glomerular filtration rate (GFR). It is 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:

\( CrCl \) — Creatinine clearance (mL/min)
\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( SCr \) — Serum creatinine (mg/dL)
\( 0.85 \) — Adjustment factor for female gender

Explanation: The formula estimates kidney function based on age, weight, serum creatinine level, and gender, with females having approximately 15% lower creatinine clearance than males.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is crucial for determining appropriate medication dosages, especially for drugs that are renally eliminated. It helps prevent drug toxicity in patients with impaired kidney 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 1-120 years, weight > 0 kg, creatinine > 0 mg/dL).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CrCl and eGFR?
A: CrCl estimates creatinine clearance using the Cockcroft-Gault formula, while eGFR estimates glomerular filtration rate using equations like CKD-EPI or MDRD.

Q2: When is Cockcroft-Gault formula preferred?
A: It is often preferred for drug dosing adjustments, especially in elderly patients and those with extremes of body weight.

Q3: 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.

Q4: Are there limitations to this formula?
A: The formula may overestimate CrCl in obese patients, patients with edema, and those with rapidly changing renal function.

Q5: Should ideal body weight be used?
A: For obese patients (BMI > 30), some guidelines recommend using ideal body weight rather than actual body weight in the calculation.