Creatinine Clearance CrCl Calculator

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):

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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 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:

\( CrCl \) — 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 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 CrCl Calculation

Details: Creatinine clearance is essential for medication dosing adjustments, particularly 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, SCr > 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 equation, while eGFR estimates glomerular filtration rate using equations like CKD-EPI or MDRD. They measure similar concepts but use different calculation methods.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for men and 85-115 mL/min for women. Values decline with age.

Q3: When is CrCl preferred over eGFR?
A: CrCl is often preferred for drug dosing adjustments, particularly for medications with narrow therapeutic windows and renal elimination.

Q4: Are there limitations to this equation?
A: The equation may overestimate CrCl in obese patients, elderly, and those with severe renal impairment. It's less accurate at extremes of age and body composition.

Q5: Should ideal body weight be used?
A: For obese patients, some guidelines recommend using ideal body weight rather than actual body weight in the calculation to avoid overestimation.