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Cockcroft-Gault Equation:
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The Cockcroft-Gault equation estimates creatinine clearance (CrCl) from serum creatinine, age, and weight. It is widely used to assess kidney function and adjust medication dosages, particularly for drugs that are renally eliminated.
The calculator uses the Cockcroft-Gault equation:
Where:
Explanation: The equation estimates glomerular filtration rate (GFR) by calculating creatinine clearance, which correlates with kidney function. The formula accounts for age-related decline in kidney function and body size.
Details: Accurate creatinine clearance estimation is essential for drug dosing adjustments, assessing kidney function in clinical practice, and identifying patients at risk for drug toxicity due to impaired renal elimination.
Tips: Enter age in years, weight in kilograms, and serum creatinine in mg/dL. All values must be valid (age between 1-120, weight > 0, creatinine > 0). For female patients, multiply the result by 0.85.
Q1: What is the difference between CrCl and eGFR?
A: CrCl estimates creatinine clearance using the Cockcroft-Gault equation, while eGFR estimates glomerular filtration rate using equations like CKD-EPI. Both assess kidney function but use different methodologies.
Q2: Why multiply by 0.85 for females?
A: Females typically have less muscle mass than males, resulting in lower creatinine production. The 0.85 multiplier adjusts for this physiological difference.
Q3: 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.
Q4: Are there limitations to this equation?
A: Less accurate in elderly, obese, malnourished patients, and those with unstable creatinine levels. It may overestimate CrCl in patients with reduced muscle mass.
Q5: When is this equation most useful?
A: Particularly valuable for drug dosing adjustments, especially for medications with narrow therapeutic windows that are primarily renally eliminated.