Cockcroft-Gault Creatinine Clearance Calculator

Cockcroft-Gault Equation:

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

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 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 provides an estimate of glomerular filtration rate.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

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

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 the inverse relationship between serum creatinine and renal function, adjusted for age-related decline in kidney function and gender differences in muscle mass.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance estimation is essential for appropriate drug dosing in patients with renal impairment, assessing kidney function, and monitoring renal toxicity from medications.

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 while eGFR estimates glomerular filtration rate. CrCl is often higher than eGFR and is preferred for drug dosing calculations.

Q2: When should ideal body weight be used instead of actual weight?
A: For obese patients (BMI > 30), ideal body weight should be used to avoid overestimating renal function. Ideal body weight can be calculated separately.

Q3: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for young adults, declining with age. Values below 60 mL/min indicate renal impairment.

Q4: Are there limitations to the Cockcroft-Gault equation?
A: Less accurate in elderly, malnourished, obese patients, and those with rapidly changing renal function or extreme muscle mass.

Q5: Why is gender correction applied?
A: Women typically have lower muscle mass than men, resulting in lower creatinine production and thus lower creatinine clearance for the same serum creatinine level.