Creatinine Creatinine Clearance Calculator

Creatinine Clearance Equation:

\[ CrCl = \frac{U_{cr} \times Urine\ Flow\ Rate}{P_{cr}} \]

Creatinine Clearance (CrCl):

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1. What is Creatinine Clearance?

Creatinine clearance is a measure of the glomerular filtration rate (GFR) that estimates how well the kidneys are filtering creatinine from the blood. It provides a more direct measurement of kidney function than serum creatinine alone.

2. How Does the Calculator Work?

The calculator uses the creatinine clearance equation:

\[ CrCl = \frac{U_{cr} \times Urine\ Flow\ Rate}{P_{cr}} \]

Where:

\( U_{cr} \) — Urine creatinine concentration (mg/dL)
\( Urine\ Flow\ Rate \) — Urine flow rate (mL/min)
\( P_{cr} \) — Plasma creatinine concentration (mg/dL)

Explanation: This equation calculates the volume of plasma that is cleared of creatinine per minute by the kidneys, providing a direct measure of renal function.

3. Importance of Creatinine Clearance

Details: Creatinine clearance is crucial for assessing kidney function, diagnosing renal impairment, monitoring disease progression, and adjusting medication dosages for drugs that are renally excreted.

4. Using the Calculator

Tips: Enter urine creatinine in mg/dL, urine flow rate in mL/min, and plasma creatinine in mg/dL. All values must be positive numbers. For accurate results, use 24-hour urine collection data.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between creatinine clearance and eGFR?
A: Creatinine clearance directly measures creatinine removal from blood using urine collection, while eGFR estimates GFR using serum creatinine and demographic factors without urine collection.

Q2: What are normal creatinine clearance values?
A: Normal values are approximately 95-125 mL/min for men and 85-115 mL/min for women. Values decrease with age and vary with muscle mass.

Q3: How is urine flow rate calculated?
A: Urine flow rate = Total urine volume (mL) ÷ Collection time (minutes). For 24-hour collection: divide total volume by 1440 minutes.

Q4: What factors affect creatinine clearance accuracy?
A: Incomplete urine collection, timing errors, dietary protein intake, muscle mass variations, and certain medications can affect accuracy.

Q5: When is creatinine clearance preferred over eGFR?
A: Creatinine clearance is preferred for drug dosing adjustments, in patients with extreme body sizes, amputees, and when precise GFR measurement is needed.