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Cockcroft-Gault Equation:
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The Cockcroft-Gault equation is a widely used formula for estimating creatinine clearance (CrCl), which serves as a surrogate for glomerular filtration rate (GFR). It was developed in 1976 and remains commonly used for drug dosing adjustments in clinical practice.
The calculator uses the Cockcroft-Gault equation:
Where:
Explanation: The equation estimates creatinine clearance based on age, weight, serum creatinine, and gender, with females having approximately 15% lower muscle mass and creatinine production.
Details: Creatinine clearance estimation is essential for drug dosing adjustments, particularly for medications with narrow therapeutic windows that are primarily eliminated by the kidneys. It helps prevent drug toxicity in patients with impaired renal function.
Tips: Enter age in years, weight in kilograms, serum creatinine in mg/dL, and select gender. All values must be valid positive numbers. Use actual body weight unless patient is significantly overweight.
Q1: What is the difference between CrCl and eGFR?
A: CrCl estimates creatinine clearance while eGFR estimates glomerular filtration rate. CrCl is often higher than GFR due to tubular secretion of creatinine.
Q2: When should ideal body weight be used?
A: For obese patients (BMI >30), some guidelines recommend using ideal body weight rather than actual weight to avoid overestimating renal function.
Q3: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for young adults, declining with age. Values below 60 mL/min indicate renal impairment.
Q4: Are there limitations to this equation?
A: The equation may overestimate CrCl in elderly, malnourished, or edematous patients, and in those with unstable renal function or extreme body weights.
Q5: Why is this still used despite newer equations?
A: Many drug dosing guidelines and clinical trials still reference Cockcroft-Gault, making it relevant for medication adjustment decisions.