1. What is the Cockcroft-Gault Equation?

The Cockcroft-Gault equation estimates creatinine clearance (CrCl), which approximates glomerular filtration rate (GFR). It's commonly used for drug dosing adjustments in patients with kidney impairment.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

Where:

• \( age \) — Age in years
• \( weight \) — Body weight in kg
• \( creatinine \) — Serum creatinine in mg/dL
• 0.85 — Adjustment factor for females

Explanation: The equation accounts for age-related decline in kidney function, body size, and gender differences in muscle mass.

3. Importance of GFR Calculation

Details: The Cockcroft-Gault estimate is widely used for drug dosing adjustments, particularly for medications that are renally excreted and have narrow therapeutic windows.

4. Using the Calculator

Tips: Enter age in years, weight in kg, 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's the difference between GFR and CrCl?
A: While often used interchangeably, CrCl typically overestimates true GFR by 10-20% due to tubular creatinine secretion.

Q2: Should ideal or actual body weight be used?
A: For obese patients, some recommend using adjusted body weight: IBW + 0.4 × (actual weight - IBW).

Q3: How accurate is this equation in elderly?
A: It may overestimate GFR in elderly due to reduced muscle mass and creatinine production.

Q4: Are there limitations to this equation?
A: Less accurate in extremes of body composition, amputees, critically ill patients, and those with rapidly changing kidney function.

Q5: Why is it still used if newer equations exist?
A: Many drug dosing guidelines are based on Cockcroft-Gault estimates, particularly for medications with narrow therapeutic windows.