Clinical Calc Creatinine Clearance

Cockcroft-Gault Equation:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

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1. What is Creatinine Clearance?

Creatinine clearance (CrCl) is a measure of kidney function that estimates the glomerular filtration rate (GFR). The Cockcroft-Gault equation is a widely used clinical tool for estimating creatinine clearance based on serum creatinine, age, weight, and gender.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault equation:

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

Where:

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

Explanation: This equation estimates the rate at which creatinine is cleared from the blood by the kidneys, providing an important measure of renal function.

3. Importance of CrCl Calculation

Details: Creatinine clearance is crucial for assessing kidney function, guiding medication dosing (especially for renally excreted drugs), and monitoring patients with renal impairment.

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 or MDRD.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 95-105 mL/min for men and 85-95 mL/min for women. Values decline with age.

Q3: When is CrCl preferred over eGFR?
A: CrCl is often preferred for drug dosing adjustments, particularly for medications with narrow therapeutic windows.

Q4: Are there limitations to the Cockcroft-Gault equation?
A: It may overestimate CrCl in obese patients, elderly, and those with unstable renal function. It's less accurate at extremes of age and body composition.

Q5: Should ideal body weight be used?
A: For obese patients, some clinicians use ideal body weight or adjusted body weight instead of actual body weight for more accurate estimation.