Creatinine Clearance (CrCl) Calculator
Estimate renal function using the Cockcroft-Gault equation for clinical assessment and medication dosage adjustments.
Enter parameters assessing
kidney function
The Cockcroft-Gault Equation
Understanding the variables that influence the estimation of creatinine clearance.
Age & Sex
Kidney function naturally declines with age. The formula subtracts age from 140 to account for this. It also applies a 0.85 multiplier for females to account for proportionally lower muscle mass.
Weight
Total body weight in kilograms is used as an estimator for muscle mass. In clinical practice, Ideal Body Weight (IBW) or Adjusted Body Weight (AdjBW) is sometimes preferred for obese patients.
Serum Creatinine
The concentration of creatinine in the blood. If kidney function is impaired, creatinine accumulates, raising the serum level and lowering the calculated CrCl.
Cockcroft-Gault Formula:
Frequently Asked Questions
What is Creatinine Clearance (CrCl)?
Creatinine clearance is an estimate of the Glomerular Filtration Rate (GFR), which measures how well the kidneys are filtering blood. It specifically estimates the rate at which creatinine (a waste product from muscle metabolism) is cleared from the blood by the kidneys.
Why is the Cockcroft-Gault formula primarily used?
The Cockcroft-Gault equation, developed in 1976, is widely used in clinical practice and pharmacology. Historically, most drug pharmacokinetic studies used this formula to determine renal dosing adjustments. Therefore, the FDA and many drug manufacturers still recommend using Cockcroft-Gault CrCl for drug dosing.
How does age and weight affect the calculation?
Creatinine is produced by muscles. As we age, muscle mass generally decreases, meaning older adults produce less creatinine. Weight is included as a surrogate for muscle mass. The formula adjusts for these factors to provide a more accurate estimate of kidney function than looking at serum creatinine alone.
Why is there a multiplier for females?
Females, on average, have a lower muscle mass compared to males of the same weight. The 0.85 multiplier in the Cockcroft-Gault formula accounts for this difference in expected creatinine production.
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