Creatinine Clearance Calculator Kidney

Cockcroft-Gault Formula:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is the Cockcroft-Gault Formula?

The Cockcroft-Gault formula 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 provides an estimate of glomerular filtration rate.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault formula:

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

Where:

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

Explanation: The formula estimates creatinine clearance based on the principle that creatinine production is proportional to muscle mass, which decreases with age and differs by gender.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is crucial for medication dosing adjustments, assessing renal function, and monitoring kidney disease progression. Many drugs require dose modification based on CrCl values.

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 formula, while eGFR estimates glomerular filtration rate using equations like CKD-EPI or MDRD. CrCl is often preferred for drug dosing.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for men and 85-115 mL/min for women. Values below these ranges may indicate impaired kidney function.

Q3: When should ideal body weight be used?
A: For obese patients (BMI > 30), ideal body weight should be used in the calculation rather than actual body weight to avoid overestimation of renal function.

Q4: Are there limitations to this formula?
A: The formula may be less accurate in elderly patients, those with extreme body weights, amputees, patients with rapidly changing renal function, and those with low muscle mass.

Q5: Why is this formula important for medication management?
A: Many medications (antibiotics, chemotherapy, etc.) require dose adjustments based on CrCl to prevent toxicity in patients with reduced renal function.