Calculating The Creatinine Clearance

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):

Unit Converter ▲

Unit Converter ▼

From:	To:

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:

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

Where:

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

Explanation: The equation estimates the rate at which creatinine is cleared from the blood by the kidneys, providing an approximation of glomerular filtration rate.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is essential for drug dosing adjustments, particularly for medications with narrow therapeutic windows that are excreted renally. 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 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. 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 instead of actual weight?
A: For obese patients (BMI > 30), ideal body weight is often recommended to avoid overestimating CrCl. Some institutions have specific protocols for weight adjustment.

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

Q5: Can this calculator be used for pediatric patients?
A: No, the Cockcroft-Gault equation is validated for adults only. Pediatric patients require age-appropriate equations for renal function estimation.