Calculator For 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 helps assess kidney function and guide medication dosing, particularly for drugs that are renally eliminated.

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
\( 0.85 \) — Female adjustment factor

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 is crucial for assessing renal function, determining appropriate drug dosages (especially for antibiotics, chemotherapeutic agents, and other renally cleared medications), and monitoring kidney disease progression.

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 one of the most widely validated formulas for estimating creatinine clearance and is commonly used for drug dosing adjustments in clinical practice.

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 this calculation be used?
A: Primarily for medication dosing adjustments, particularly for drugs with narrow therapeutic windows that are eliminated by the kidneys.

Q4: Are there limitations to this formula?
A: Less accurate in extremes of body weight, elderly patients, patients with unstable creatinine levels, amputees, and those with severe malnutrition or obesity.

Q5: How does this differ from eGFR?
A: CrCl estimates actual creatinine clearance, while eGFR estimates glomerular filtration rate standardized to body surface area. They serve different clinical purposes.