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Formula used
Cockcroft–Gault estimated creatinine clearance
The Cockcroft–Gault equation estimates creatinine clearance from age, weight, serum creatinine, and the equation’s sex adjustment. Its result is expressed in millilitres per minute and is not indexed to body surface area. The selected body weight can substantially change the final estimate.
Timed urine creatinine clearance
A timed urine calculation uses urine creatinine concentration, total collected volume, collection duration, and serum creatinine. The urine and blood specimens should represent the same physiologic period whenever possible. Missed urine, timing mistakes, or unit errors can distort results.
Body surface area conversion
How to use this calculator
- Select Cockcroft–Gault or timed urine clearance.
- Enter age, the applicable equation sex factor, height, weight, and serum creatinine.
- Select the original measurement units instead of converting values manually.
- For Cockcroft–Gault, choose the body-weight method required by your policy or dosing source.
- For measured clearance, enter urine creatinine, total volume, and exact collection duration.
- Add optional cystatin C to display the combined 2021 CKD-EPI comparison.
- Mark relevant caution flags and adjust non-diagnostic comparison thresholds when needed.
- Review the substituted formula, steps, unit conversions, warnings, and comparison values.
- Use copy, CSV, PDF, or print controls to retain a calculation summary without identifiers.
Example data
| Example | Method | Inputs | Purpose |
|---|---|---|---|
| Adult estimate | Cockcroft–Gault | Age 65, male factor, 75 kg, 170 cm, SCr 1.1 mg/dL | Demonstrate weight-derived CrCl and eGFR comparison |
| Unit conversion | Cockcroft–Gault | Age 54, female factor, 165 lb, 5 ft 5 in, SCr 106 µmol/L | Demonstrate automatic SI and conventional-unit conversion |
| Timed collection | Timed urine | UCr 100 mg/dL, volume 1500 mL, 24 hours, SCr 1.1 mg/dL | Demonstrate urine flow and measured clearance steps |
Understanding the result
Creatinine clearance and estimated glomerular filtration rate describe related but distinct kidney-function estimates. Cockcroft–Gault includes body weight, while modern CKD-EPI equations use standardized creatinine with age and an equation sex factor. Their numbers should not be exchanged without checking the intended application.
The calculator shows both indexed and individual-body-size eGFR comparison values when adult inputs are available. Indexed values support comparisons across people, while de-indexed values reflect the entered body surface area. Medication decisions still require the current drug label and clinical context.
Serum creatinine can be affected by muscle mass, diet, body size, secretion, and changing kidney function. Estimates may be misleading during acute changes or in people with unusual body composition. More direct assessment may be necessary near important decision thresholds.
Frequently asked questions
Is creatinine clearance the same as eGFR?
No. They use different equations, validation targets, units, and body-size conventions, so the calculator displays them separately.
Which body weight should be used?
The required weight depends on the clinical policy, medicine source, and patient characteristics. This calculator exposes every method instead of silently choosing one.
What does automatic weight selection do?
It uses adjusted weight when actual weight exceeds 120% of calculated ideal weight; otherwise it uses actual weight. This convenience rule should not replace local guidance.
Does the calculator round low serum creatinine upward?
No. It uses the entered positive serum creatinine and does not apply an undocumented minimum or age-based rounding rule.
Can µmol/L be entered directly?
Yes. Serum creatinine in µmol/L is divided by 88.4 internally before equations requiring mg/dL are calculated.
How is timed urine clearance calculated?
The calculator converts concentration and volume units, calculates urine flow per minute, and divides the urine creatinine product by serum creatinine.
Why is cystatin C optional?
Cystatin C is not part of Cockcroft–Gault. When supplied, it enables the race-free 2021 combined creatinine–cystatin C eGFR comparison.
What are the three threshold fields?
They are editable comparison markers that classify the calculated number relative to user-entered cutoffs. They do not provide drug-specific dosing instructions.
Can this calculator be used for children?
It displays an age warning because the included Cockcroft–Gault and CKD-EPI equations are adult methods. Use a validated pediatric equation instead.
Does this page save patient data?
No database or logging code is included in this file. Server and hosting configurations should still be reviewed before clinical deployment.
Limitations and medical disclaimer
This calculator is an educational and verification aid, not a medical device or independent prescribing system. It cannot determine whether a specimen is accurate, a collection is complete, or kidney function is stable. A qualified clinician must interpret every result in context.
Do not use this page alone to diagnose kidney disease, choose dialysis, or change a medication dose. Confirm the equation and units specified by the current drug label, laboratory, protocol, or specialist. Urgent symptoms or rapidly changing laboratory values require direct medical assessment.