1. What is Urine Creatinine Clearance?

Urine Creatinine Clearance (CrCl) is a measured estimate of glomerular filtration rate (GFR) using 24-hour urine collection. It provides a direct measurement of kidney function by calculating how effectively the kidneys clear creatinine from the blood.

2. How Does the Calculator Work?

The calculator uses the urine creatinine clearance formula:

Where:

• \( Ucr \) — Urine creatinine concentration (mg/dL)
• \( V \) — Urine volume (mL)
• \( Scr \) — Serum creatinine concentration (mg/dL)
• \( t \) — Collection time (minutes; typically 1440 for 24 hours)

Explanation: This formula calculates the volume of plasma cleared of creatinine per minute, providing a direct measurement of kidney filtration capacity.

3. Importance of Measured Creatinine Clearance

Details: Measured creatinine clearance is considered more accurate than estimated equations in specific clinical situations, particularly for drug dosing in patients with unstable kidney function or unusual body composition.

4. Using the Calculator

Tips: Enter urine creatinine in mg/dL, urine volume in mL, serum creatinine in mg/dL, and collection time in minutes (1440 for 24-hour collection). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why use measured CrCl instead of estimated GFR?
A: Measured CrCl is more accurate in patients with extreme muscle mass, amputations, rapidly changing kidney function, or when precise drug dosing is critical.

Q2: How should urine collection be performed?
A: Collect all urine for 24 hours, discard first morning void, then collect all urine including next morning's first void. Keep collection container refrigerated.

Q3: What are normal CrCl values?
A: Normal range is approximately 90-130 mL/min for young adults, declining with age. Values below 60 mL/min indicate impaired kidney function.

Q4: What factors can affect accuracy?
A: Incomplete urine collection, improper timing, meat consumption before testing, and certain medications can affect results.

Q5: When is this test most useful?
A: Particularly valuable for dosing nephrotoxic drugs, evaluating kidney donors, and monitoring patients with rapidly changing kidney function.