How to Calculate CrCl

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 Formula?

The Cockcroft-Gault formula estimates creatinine clearance (CrCl) from serum creatinine, age, weight, and gender. It is widely used for drug dosing adjustments in patients with impaired kidney function and for assessing renal 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:

\( CrCl \) — Creatinine clearance (mL/min)
\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( SCr \) — Serum creatinine (mg/dL)
0.85 — Female multiplier

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

3. Importance of CrCl Calculation

Details: Accurate CrCl estimation is essential for appropriate drug dosing of renally eliminated medications, assessing kidney function, and monitoring patients with chronic kidney disease.

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: Why use Cockcroft-Gault formula?
A: It is one of the most widely validated equations for drug dosing adjustments and is commonly referenced in medication guidelines and prescribing information.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 90-120 mL/min for young adults. Values decline with age, and below 60 mL/min may indicate impaired kidney function.

Q3: When should creatinine be measured?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise as these can temporarily increase creatinine levels.

Q4: Are there limitations to this formula?
A: Less accurate in extremes of age, obesity, malnutrition, amputees, pregnant women, and those with rapidly changing kidney function or unstable creatinine levels.

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 for more accurate estimation.