Clin Calc Creatinine Clearance Calculator

Cockcroft-Gault Formula:

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

Age:

years

Weight:

Serum Creatinine:

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) from serum creatinine, age, weight, and gender. It provides an estimate of kidney function and 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:

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

Where:

\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( Serum\ Cr \) — Serum creatinine in mg/dL
\( 0.85 \) — Correction factor for female gender
\( 72 \) — Constant factor in the denominator

Explanation: The formula estimates creatinine clearance based on the premise that creatinine production is proportional to muscle mass, which decreases with age and differs between genders.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance estimation is crucial for assessing renal function, determining appropriate drug dosages for medications cleared by the kidneys, 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: 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. They measure different aspects of kidney function.

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 decrease with age.

Q3: When is ideal body weight used instead of actual weight?
A: For obese patients (BMI > 30), some clinicians use ideal body weight to avoid overestimating CrCl. The decision depends on institutional protocols.

Q4: What are the limitations of the Cockcroft-Gault formula?
A: Less accurate in elderly patients, those with extreme body weights, amputees, patients with rapidly changing renal function, and those with unstable creatinine levels.

Q5: Why is this formula still used despite newer equations?
A: Many drug dosing guidelines and clinical trials still reference Cockcroft-Gault, making it relevant for medication adjustment decisions.