Enter patient values
Use current creatinine, a known baseline, a 48-hour comparator, body weight, and urine totals. The page stays single column, while the form fields collapse from three columns to one on smaller screens.
Formula used
Current creatinine ÷ baseline creatinine
Current creatinine − creatinine from 48 hours earlier
Total urine volume ÷ (body weight × hours observed)
Overall AKI stage = highest stage reached by creatinine, urine output, or renal replacement therapy.
The calculator compares each entered metric against standard staging thresholds, then reports the highest qualifying stage with supporting notes.
How to use this calculator
- Choose one creatinine unit and keep every creatinine value in that same unit.
- Enter the current creatinine. Add a baseline if one is known.
- Enter the creatinine from 48 hours earlier when that comparison exists.
- Enter body weight before adding urine totals, because urine staging uses mL/kg/h.
- Add urine volumes for 6, 12, and 24 hours if those observation windows are available.
- Enter anuria duration and indicate whether renal replacement therapy was initiated.
- Press Calculate stage to display the result above the form.
- Use the CSV or PDF buttons to export the result summary after calculation.
Example data table
| Scenario | Current creatinine | Baseline creatinine | 48-hour creatinine | Weight | Urine 6h | Urine 12h | Urine 24h | Anuria | RRT | Expected stage |
|---|---|---|---|---|---|---|---|---|---|---|
| Mild rise with low 6-hour urine | 1.6 mg/dL | 1.0 mg/dL | 1.2 mg/dL | 70 kg | 180 mL | 520 mL | 1,150 mL | 0 h | No | Stage 1 |
| Twofold rise with sustained oliguria | 2.4 mg/dL | 1.1 mg/dL | 2.1 mg/dL | 80 kg | 300 mL | 360 mL | 780 mL | 0 h | No | Stage 2 |
| Marked rise with anuria and dialysis | 4.5 mg/dL | 1.2 mg/dL | 4.0 mg/dL | 75 kg | 20 mL | 40 mL | 80 mL | 12 h | Yes | Stage 3 |
Staging thresholds used in this tool
| Stage | Creatinine criteria | Urine output criteria | Therapy criterion |
|---|---|---|---|
| Stage 1 | Rise of at least 0.3 mg/dL in 48 hours, or 1.5–1.9 × baseline | Below 0.5 mL/kg/h for 6–12 hours | Not required |
| Stage 2 | 2.0–2.9 × baseline | Below 0.5 mL/kg/h for 12 hours or longer | Not required |
| Stage 3 | At least 3.0 × baseline, or at least 4.0 mg/dL | Below 0.3 mL/kg/h for 24 hours, or anuria for 12 hours | Renal replacement therapy initiated |
Frequently asked questions
1. What does this calculator classify?
It classifies acute kidney injury stage from entered serum creatinine changes, urine output trends, and dialysis status, then reports the highest qualifying stage.
2. Can urine output alone stage AKI?
Yes. Reduced urine output can stage AKI even when creatinine data are incomplete. That is why body weight and observed hours are included.
3. Why is body weight required?
Urine criteria are normalized to mL per kilogram per hour. Without weight, the calculator cannot correctly interpret urine output thresholds.
4. What if the baseline creatinine is unknown?
The tool can still use the 48-hour rise and urine output data, but ratio-based creatinine staging may be incomplete or understated.
5. Does a high creatinine always mean AKI?
No. A high creatinine may also reflect chronic kidney disease or mixed pathology. Clinical context, prior labs, and trend review remain essential.
6. How is the overall stage selected?
The overall stage is simply the highest stage reached by the entered creatinine rule, urine output rule, or renal replacement therapy status.
7. Are the CSV and PDF files generated online?
No. They are generated in the browser from the visible result summary, which makes quick exporting easy during review sessions.
8. Should treatment decisions rely on this page alone?
No. It is a structured staging aid, not a standalone diagnostic or treatment system. Confirm with full clinical assessment and validated lab data.