Calculator
Example Data Table
| Urine creatinine | Serum creatinine | Urine volume | Time | Height | Weight | Age | Expected result |
|---|---|---|---|---|---|---|---|
| 100 mg/dL | 1.0 mg/dL | 1500 mL | 24 hours | 170 cm | 70 kg | 50 | 104.17 mL/min uncorrected |
| 9 mmol/L | 88.4 µmol/L | 1.4 L | 24 hours | 165 cm | 62 kg | 45 | 98.98 mL/min uncorrected |
| 80 mg/dL | 1.2 mg/dL | 1200 mL | 12 hours | 180 cm | 85 kg | 60 | 111.11 mL/min uncorrected |
Formula Used
Uncorrected creatinine clearance:
CrCl = (Urine creatinine × Urine volume) ÷ (Serum creatinine × Collection time)
BSA corrected clearance:
Corrected CrCl = Uncorrected CrCl × 1.73 ÷ Body surface area
Body surface area:
BSA = square root of ((Height in cm × Weight in kg) ÷ 3600)
Cockcroft-Gault comparison:
CrCl = ((140 − Age) × Weight in kg × Sex factor) ÷ (72 × Serum creatinine)
The female sex factor is 0.85. The male sex factor is 1.
How to Use This Calculator
Enter the urine creatinine value from the timed urine test.
Enter the matching serum creatinine value from the blood test.
Add the total urine volume collected during the full period.
Enter collection hours and any extra minutes.
Add height and weight when you need BSA correction.
Add age, sex, and weight for the comparison estimate.
Press calculate. The result appears above the form.
Use CSV or PDF export to save the result.
Understanding Urine Creatinine Clearance
Urine creatinine clearance estimates how much blood plasma is cleared of creatinine each minute. It uses a timed urine collection and a matching serum creatinine result. The value can help compare measured kidney filtration with an estimated value from age, weight, sex, and serum creatinine. It is not a diagnosis by itself.
Why Timed Collection Matters
A timed urine sample must include all urine passed during the chosen period. A missed void can lower the result. Extra urine from outside the period can raise it. For many checks, a 24 hour collection is used. Shorter periods can work, but they need careful timing and clear labels.
What This Tool Calculates
This calculator accepts urine creatinine, serum creatinine, urine volume, and collection time. It returns uncorrected creatinine clearance in mL per minute. It can also correct the value to a standard body surface area of 1.73 square meters. Height and weight are used for that correction. Age, sex, and weight can add a Cockcroft-Gault comparison.
Reading the Result
A higher or lower result should be reviewed with clinical context. Hydration, muscle mass, diet, pregnancy, recent exercise, medicines, and collection quality can affect creatinine values. The corrected result is useful when comparing people of different body sizes. The uncorrected result may be useful for some dosing discussions. Always follow the method requested by the lab or clinician.
Practical Tips
Enter units carefully before calculating. Use the same collection period shown on the lab form. Check that the total volume includes the whole container. Record height and weight when correction is needed. Save the CSV or PDF report for a visit, chart note, or repeat comparison.
Limitations
Creatinine clearance can overestimate true filtration because creatinine is also secreted by kidney tubules. Results may be less reliable during rapidly changing kidney function. They may also vary after intense exercise or unusual meat intake. This page is for education and planning. Medical decisions should be made with qualified care.
Quality Checks
The tool also shows urine flow and creatinine excretion. These values help spot unusual entries. A very small volume, very short time, or impossible unit choice should be checked before using the answer. Repeat tests should use one method.
FAQs
What is urine creatinine clearance?
It is an estimate of how much plasma is cleared of creatinine each minute. It uses urine creatinine, serum creatinine, urine volume, and collection time.
Does this replace medical advice?
No. It is an educational tool. Kidney results should be reviewed with a qualified clinician, especially when values are abnormal or symptoms are present.
Why does collection time matter?
The formula uses urine flow per minute. A wrong time changes the flow rate and can make clearance look too high or too low.
What is BSA correction?
BSA correction adjusts clearance to a standard body surface area of 1.73 square meters. It helps compare results across different body sizes.
Can I use a 12 hour collection?
Yes, if your lab or clinician requested it. Enter the exact collection time. A 24 hour collection is often used for routine measured clearance.
Why include Cockcroft-Gault?
It gives an estimated creatinine clearance from age, sex, weight, and serum creatinine. It is useful as a comparison, not a timed urine measurement.
Which unit should I choose?
Choose the unit printed on your lab report. The calculator converts supported creatinine units internally before calculating the result.
Why are my results different from the lab?
Differences may come from rounding, unit choices, BSA correction, collection errors, or lab-specific methods. Use the lab report as the clinical reference.