1. What is Creatinine Clearance?

Creatinine clearance is a measure of the glomerular filtration rate (GFR) and represents the volume of blood plasma that is cleared of creatinine per unit time. It is used to assess renal function and is particularly important for drug dosing in patients with impaired kidney function.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault formula:

For females, the result is multiplied by 0.85.

Where:

• \( Age \) — Age in years
• \( Weight \) — Body weight in kilograms
• \( SCr \) — Serum creatinine in µmol/L
• \( 1.23 \) — Conversion factor for SI units
• \( 0.85 \) — Female adjustment factor

Explanation: This equation estimates creatinine clearance based on age, weight, serum creatinine level, and gender, providing a practical assessment of kidney function.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is essential for determining appropriate drug dosages, monitoring kidney function in chronic kidney disease, and assessing renal impairment in various clinical conditions.

4. Using the Calculator

Tips: Enter age in years, weight in kilograms, serum creatinine in µmol/L, and select gender. All values must be valid positive numbers for accurate calculation.

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.

Q2: When is creatinine clearance preferred over eGFR?
A: CrCl is often preferred for drug dosing adjustments, particularly for medications with narrow therapeutic windows and renal elimination.

Q3: What are normal creatinine clearance values?
A: Normal values are approximately 95-125 mL/min for men and 85-115 mL/min for women, decreasing with age.

Q4: Are there limitations to the Cockcroft-Gault formula?
A: It may overestimate CrCl in obese patients, elderly, and those with reduced muscle mass, and may be less accurate in hospitalized patients.

Q5: How often should creatinine clearance be measured?
A: Frequency depends on clinical context - regularly in CKD patients, before starting nephrotoxic drugs, and when significant changes in renal function are suspected.