1. What is Creatinine Clearance?

Creatinine clearance (CrCl) is a measure of kidney function that estimates the volume of blood plasma cleared of creatinine per minute. It's commonly used to assess renal function before drug dosing.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

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 equation estimates creatinine clearance based on age, weight, serum creatinine, and gender, with lower values expected in women due to typically smaller muscle mass.

3. Importance of CrCl Calculation

Details: Creatinine clearance is crucial for adjusting medication dosages in patients with impaired kidney function, particularly for drugs that are renally excreted.

4. Using the Calculator

Tips: Enter age in years, weight in kg, serum creatinine in mg/dL, and select gender. All values must be valid (age 1-120, weight > 0, SCr > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why use Cockcroft-Gault instead of eGFR?
A: While eGFR is better for staging CKD, Cockcroft-Gault is still widely used for drug dosing adjustments due to its historical validation in pharmacokinetic studies.

Q2: What are normal CrCl values?
A: Normal is approximately 95-125 mL/min for young men and 85-115 mL/min for young women, declining with age.

Q3: When should creatinine be measured?
A: Morning fasting sample is ideal, but random samples are acceptable. Avoid testing after meat-heavy meals or vigorous exercise.

Q4: Are there limitations to this equation?
A: Less accurate in extremes of age/weight, obese patients, amputees, and those with rapidly changing kidney function or very low muscle mass.

Q5: Should I use actual or ideal body weight?
A: For obese patients (BMI >30), consider using ideal body weight or adjusted body weight for more accurate results.