Urinary Creatinine Clearance Calculator

Creatinine Clearance Formula:

\[ CrCl = \frac{U_{cr} \times V}{P_{cr} \times Time} \]

Urine Creatinine (U_cr):

mg/dL

Urine Volume (V):

Plasma Creatinine (P_cr):

mg/dL

Collection Time:

minutes

Creatinine Clearance (CrCl):

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1. What is Urinary Creatinine Clearance?

Urinary creatinine clearance is a measure of the glomerular filtration rate (GFR) calculated from creatinine concentrations in urine and plasma, along with urine volume collected over a specific time period. It provides a direct assessment of kidney function.

2. How Does the Calculator Work?

The calculator uses the creatinine clearance formula:

\[ CrCl = \frac{U_{cr} \times V}{P_{cr} \times Time} \]

Where:

\( U_{cr} \) — Urine creatinine concentration (mg/dL)
\( V \) — Urine volume (mL)
\( P_{cr} \) — Plasma creatinine concentration (mg/dL)
\( Time \) — Collection time (minutes)

Explanation: This formula calculates the volume of plasma cleared of creatinine per minute, providing a direct measure of glomerular filtration rate.

3. Importance of Creatinine Clearance

Details: Creatinine clearance is crucial for assessing kidney function, monitoring renal disease progression, adjusting drug dosages in renal impairment, and evaluating transplant kidney function.

4. Using the Calculator

Tips: Enter urine creatinine in mg/dL, urine volume in mL, plasma creatinine in mg/dL, and collection time in minutes. For 24-hour collections, use 1440 minutes. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CrCl and eGFR?
A: CrCl is measured from urine collection, while eGFR is estimated from serum creatinine using equations. CrCl is more accurate but requires urine collection.

Q2: How long should urine be collected?
A: 24-hour collections are standard, but shorter periods (2-8 hours) can be used with proper timing and complete collection.

Q3: What are normal creatinine clearance values?
A: Normal range is 90-120 mL/min for young adults, decreasing with age. Values below 60 mL/min suggest renal impairment.

Q4: What factors affect creatinine clearance accuracy?
A: Incomplete urine collection, meat consumption, exercise, medications, and muscle mass can affect results.

Q5: When is creatinine clearance preferred over eGFR?
A: In patients with extremes of muscle mass, amputees, rapidly changing renal function, or when precise drug dosing is critical.