Renal Calculator Creatinine Clearance

Cockcroft-Gault Formula:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is the Cockcroft-Gault 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 glomerular filtration rate 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:

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

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 formula estimates creatinine clearance based on the principle 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: Why use Cockcroft-Gault formula?
A: It's a well-validated method for estimating creatinine clearance and is widely used in clinical practice, especially for drug dosing adjustments.

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 this calculation be used?
A: Primarily for drug dosing in patients with renal impairment, monitoring kidney function in chronic disease, and preoperative assessments.

Q4: Are there limitations to this formula?
A: Less accurate in extremes of age, obesity, malnutrition, amputees, and patients with rapidly changing renal function or muscle mass.

Q5: How does this differ from eGFR?
A: CrCl estimates actual clearance while eGFR estimates standardized GFR. Many drug dosing guidelines still reference CrCl rather than eGFR.