Mayo Clinic Creatinine Clearance Calculator

Mayo-Modified Cockcroft-Gault Equation:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is the Mayo-Modified Cockcroft-Gault Equation?

The Mayo-modified 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 provides a practical estimate of kidney function.

2. How Does the Calculator Work?

The calculator uses the Mayo-modified Cockcroft-Gault equation:

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

Where:

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

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

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is essential for drug dosing adjustments, assessing renal function, and monitoring patients with kidney disease. Many medications 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 equation, while eGFR estimates glomerular filtration rate using equations like CKD-EPI. They serve similar purposes but use different calculation methods.

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

Q3: When should this equation not be used?
A: Avoid in patients with rapidly changing creatinine levels, amputees, severe obesity, malnutrition, or muscle wasting diseases.

Q4: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for men and 85-115 mL/min for women, declining with age.

Q5: How accurate is this equation for drug dosing?
A: It is widely accepted for drug dosing adjustments, though in critical situations or extremes of body habitus, measured creatinine clearance may be preferred.