Medcalc Creatinine Clearance Calculator

Cockcroft-Gault Equation:

\[ CrCl = \frac{(140 - Age) \times Weight}{72 \times Scr} \times (0.85 \text{ if female}) \]

Age:

years

Weight:

Serum Creatinine (Scr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is the Cockcroft-Gault Equation?

The Cockcroft-Gault equation estimates creatinine clearance (CrCl) from serum creatinine, age, weight, and gender. It is widely used for drug dosing adjustments in patients with renal impairment and for assessing kidney function.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

\[ CrCl = \frac{(140 - Age) \times Weight}{72 \times Scr} \times (0.85 \text{ if female}) \]

Where:

\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( Scr \) — Serum creatinine in mg/dL
0.85 — Correction factor for female gender

Explanation: The equation estimates the glomerular filtration rate based on creatinine production and elimination, with adjustments for age-related decline in muscle mass and gender differences.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is crucial for determining appropriate drug dosages for medications that are renally eliminated, assessing kidney function, and monitoring patients with chronic kidney disease.

4. Using the Calculator

Tips: Enter age in years, weight in kilograms, 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 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. CrCl is often preferred for drug dosing.

Q2: 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.

Q3: When should ideal body weight be used instead of actual weight?
A: For obese patients (BMI > 30), ideal body weight is often recommended to avoid overestimating CrCl. Ideal body weight can be calculated separately.

Q4: Are there limitations to this equation?
A: Less accurate in elderly patients, those with extreme body weights, muscle wasting conditions, rapidly changing renal function, or unstable creatinine levels.

Q5: Why is the female correction factor 0.85?
A: Women typically have less muscle mass than men, resulting in lower creatinine production. The 0.85 factor accounts for this physiological difference.