Adult Creatinine Clearance Calculator

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 is a widely used method for estimating creatinine clearance (CrCl) in adults. It provides an estimate of glomerular filtration rate based on serum creatinine, age, weight, and gender, and is commonly used for drug dosing adjustments in patients with renal impairment.

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:

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

Explanation: The formula accounts for age-related decline in renal function, body size, and gender differences in muscle mass and creatinine production.

3. Importance of Creatinine Clearance

Details: Creatinine clearance estimation is crucial for drug dosing adjustments, assessing renal function, and monitoring patients with kidney disease. Many medications require dose modification based on CrCl values to prevent toxicity.

4. Using the Calculator

Tips: Enter age (must be 18 years or older), weight in kilograms, serum creatinine in mg/dL, and select gender. All values must be valid positive numbers.

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. They serve similar purposes but use different calculation methods.

Q2: Why is weight included in the formula?
A: Weight is included because creatinine production is proportional to muscle mass, which correlates with body weight.

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 formula?
A: The formula may overestimate CrCl in obese patients, elderly, those with extreme muscle mass, or patients with unstable renal function.

Q5: When should ideal body weight be used?
A: For obese patients (BMI >30), some guidelines recommend using ideal body weight rather than actual weight for more accurate estimation.