Clinical Calc Creatinine Clearance

Cockcroft-Gault Clinical 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 clinical tool for estimating creatinine clearance (CrCl) from serum creatinine, age, weight, and gender. It helps assess kidney function and guide medication dosing in clinical practice.

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 estimates the rate at which creatinine is cleared from the blood by the kidneys, providing an approximation of glomerular filtration rate.

3. Importance of Creatinine Clearance Calculation

Details: Creatinine clearance is essential for assessing renal function, determining appropriate drug dosages (especially for renally excreted medications), and monitoring kidney disease progression.

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 1-120 years, weight > 0 kg, SCr > 0 mg/dL).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CrCl and eGFR?
A: CrCl estimates creatinine clearance specifically, while eGFR estimates glomerular filtration rate. CrCl is often used for drug dosing, while eGFR is used for CKD staging.

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 decline with age.

Q3: When is the Cockcroft-Gault formula most accurate?
A: It works best in stable outpatients with normal muscle mass and relatively stable renal function.

Q4: What are the limitations of this formula?
A: Less accurate in elderly, obese, malnourished patients, amputees, and those with rapidly changing renal function or extreme body weights.

Q5: Why is weight included in the calculation?
A: Weight helps account for muscle mass, which affects creatinine production. Ideal body weight may be used in obese patients for more accurate results.