How To Calc Creatinine Clearance

Cockcroft-Gault Formula:

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

Age:

years

Weight:

Serum Creatinine (SCr):

mg/dL

Gender:

Creatinine Clearance (CrCl):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Creatinine Clearance?

Creatinine clearance (CrCl) is a measure of the glomerular filtration rate (GFR) that estimates how well the kidneys are filtering creatinine from the blood. The Cockcroft-Gault formula is widely used to calculate creatinine clearance based on age, weight, serum creatinine, and gender.

2. How Does the Calculator Work?

The calculator uses the Cockcroft-Gault formula:

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

Where:

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

Explanation: This formula estimates the rate at which creatinine is cleared from the blood, providing an approximation of kidney function.

3. Importance of CrCl Calculation

Details: Creatinine clearance is crucial for assessing kidney function, determining appropriate drug dosages (especially for medications cleared by the kidneys), 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, SCr > 0).

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

Q3: When is CrCl calculation most important?
A: Particularly important for drug dosing in patients with renal impairment, elderly patients, and when prescribing nephrotoxic medications.

Q4: What are the limitations of the Cockcroft-Gault formula?
A: Less accurate in extremes of body weight, elderly patients, patients with unstable creatinine levels, and those with severe renal impairment.

Q5: Should ideal body weight be used?
A: For obese patients, some guidelines recommend using ideal body weight rather than actual body weight for more accurate calculation.