24 Hour Creatinine Clearance Calculator

24-Hour Creatinine Clearance Equation:

\[ CrCl = \frac{U_{cr} \times V}{P_{cr} \times 1440} \]

Creatinine Clearance (CrCl):

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1. What is 24-Hour Creatinine Clearance?

The 24-hour creatinine clearance test measures how well the kidneys are clearing creatinine from the blood. It provides a more accurate assessment of glomerular filtration rate (GFR) than estimated equations and is considered the gold standard for measuring kidney function.

2. How Does the Calculator Work?

The calculator uses the 24-hour creatinine clearance formula:

\[ CrCl = \frac{U_{cr} \times V}{P_{cr} \times 1440} \]

Where:

\( CrCl \) — Creatinine clearance (mL/min)
\( U_{cr} \) — Urine creatinine concentration (mg/dL)
\( V \) — 24-hour urine volume (mL)
\( P_{cr} \) — Plasma creatinine concentration (mg/dL)
\( 1440 \) — Minutes in 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 Creatinine Clearance Calculation

Details: 24-hour creatinine clearance is essential for accurate assessment of kidney function, particularly in patients with unstable creatinine levels, extremes of body size, or when precise medication dosing is required for renally excreted drugs.

4. Using the Calculator

Tips: Enter urine creatinine in mg/dL, 24-hour urine volume in mL, and plasma creatinine in mg/dL. Ensure all values are from the same 24-hour collection period and that the urine collection was complete and accurately timed.

5. Frequently Asked Questions (FAQ)

Q1: Why is 24-hour collection necessary?
A: It accounts for diurnal variations in creatinine excretion and provides an integrated measure of kidney function over a full day.

Q2: What are normal creatinine clearance values?
A: Normal range is approximately 90-130 mL/min for men and 80-125 mL/min for women, varying with age and muscle mass.

Q3: How to ensure accurate 24-hour urine collection?
A: Discard first morning urine, note the time, collect all urine for next 24 hours including first morning urine the next day, keep collection container refrigerated.

Q4: When is 24-hour creatinine clearance preferred over eGFR?
A: In patients with unstable renal function, amputees, severe malnutrition, obesity, pregnancy, or when precise drug dosing is critical.

Q5: What factors can affect creatinine clearance results?
A: Incomplete urine collection, meat consumption, exercise, certain medications, and timing of blood draw relative to urine collection.