1. What is the Cockcroft-Gault Equation?

The Cockcroft-Gault equation estimates creatinine clearance (CrCl), which approximates glomerular filtration rate (GFR). It was developed in 1973 and is commonly used for drug dosing adjustments.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

Where:

• \( Age \) — Age in years
• \( Weight \) — Body weight in kilograms
• \( Cr \) — Serum creatinine (mg/dL)
• 0.85 — Female multiplier

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

3. Importance of GFR Calculation

Details: While not as accurate as newer equations for estimating true GFR, Cockcroft-Gault remains widely used for medication dosing, particularly for drugs with narrow therapeutic windows.

4. Using the Calculator

Tips: Enter age in years, weight in kg, 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: Should I use actual or ideal body weight?
A: For obese patients, consider using ideal body weight or adjusted body weight. Consult clinical guidelines for specific recommendations.

Q2: How does this compare to CKD-EPI or MDRD?
A: Cockcroft-Gault estimates creatinine clearance rather than GFR directly. It tends to overestimate GFR compared to more modern equations.

Q3: What are normal CrCl values?
A: Normal is approximately 90-120 mL/min for young adults, decreasing with age. Values below 60 may indicate impaired kidney function.

Q4: When is this equation most useful?
A: Primarily for drug dosing adjustments, especially for medications that are renally excreted and have narrow therapeutic ranges.

Q5: What are the limitations?
A: Less accurate in elderly, malnourished, amputees, those with unstable creatinine, or at extremes of body size.