Calculator For Creatinine Clearance

Cockcroft-Gault Formula:

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

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), which serves as an approximation of glomerular filtration rate (GFR). It was developed in 1976 and remains commonly used for drug dosing adjustments in patients with renal impairment.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault formula:

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

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 inverse relationship between serum creatinine and renal function, adjusted for age, weight, and gender.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance estimation is essential for assessing renal function, guiding drug dosing (especially for renally excreted medications), and evaluating 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 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 or MDRD. They serve similar purposes but use different calculations.

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 below these ranges may indicate impaired renal function.

Q3: When is Cockcroft-Gault preferred over other equations?
A: Cockcroft-Gault is often preferred for drug dosing adjustments, particularly in older medications and clinical trials where it was the standard.

Q4: Are there limitations to this formula?
A: The formula may overestimate CrCl in obese patients, elderly, those with muscle wasting, and in hospitalized patients. It assumes stable renal function.

Q5: Should ideal body weight be used?
A: For obese patients (BMI > 30), some guidelines recommend using ideal body weight rather than actual weight in the calculation.