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Classifies acute kidney injury (AKI) severity using the KDIGO 2012 criteria based on serum creatinine changes and urine output. The highest applicable stage is assigned when multiple criteria are met.
Clinical decision-support tool for qualified healthcare professionals. Results are not a diagnosis and should not replace professional clinical judgment.
The KDIGO (Kidney Disease: Improving Global Outcomes) 2012 framework classifies acute kidney injury (AKI) severity into stages 1–3 using two independent sets of criteria: serum creatinine (an absolute rise of ≥0.3 mg/dL within 48 hours, or a rise of 1.5–1.9×, 2.0–2.9×, or ≥3.0× baseline within 7 days) and urine output (oliguria thresholds expressed per mL/kg/h over specified durations). Staging classifies severity and risk; it does not, by itself, establish the cause of AKI. The staging result depends on which baseline creatinine is used, and the true baseline is often unknown at presentation, particularly when the current value is already elevated. An estimated baseline can be substituted (e.g., the lowest creatinine in the preceding 7 days), but this introduces uncertainty that can shift the assigned stage; the same creatinine pair can produce a different stage depending on the baseline chosen. Urine output criteria must be interpreted with caution. They reflect recent volume status, the presence of diuretics, bladder catheter patency, and the accuracy of the recorded output as much as intrinsic kidney function, and brief or ambiguous low-output readings can misclassify the stage. Staging identifies whether AKI is present and its severity; it does not identify AKI etiology (whether the injury is prerenal, intrinsic, or postrenal), and it does not itself prescribe a specific treatment. The KDIGO framework is intended primarily for adults; pediatric and pregnancy-specific frameworks use separate definitions, and some special populations require alternative criteria. Trends over time matter as much as the single calculated stage: a changing creatinine trajectory and the clinical context should guide interpretation rather than the number alone.
Specialty
NephrologyCategory
NephrologyDifficulty
Basic
Estimated Time
30 seconds
Version
1.0
Last Updated
2026-08
Formula
Keywords
Normal Range
No AKI
| Classification | Range |
|---|---|
No AKI | None |
Stage 1 | Cr ≥0.3 mg/dL rise or 1.5–1.9× baseline; UO <0.5 mL/kg/h 6–12h |
Stage 2 | Cr 2.0–2.9× baseline; UO <0.5 mL/kg/h ≥12h |
Stage 3 | Cr ≥3.0× baseline or ≥4.0 mg/dL or RRT; UO <0.3 mL/kg/h ≥24h or anuria ≥12h |
Classifies acute kidney injury (AKI) severity using the KDIGO 2012 criteria based on serum creatinine changes and urine output.
KDIGO AKI staging assigns the highest stage met by creatinine or urine-output criteria. Creatinine: stage 1 = rise of 0.3 mg/dL or more or 1.5-1.9x baseline, stage 2 = 2.0-2.9x baseline, stage 3 = 3.0x baseline or more, current creatinine 4.0 mg/dL or more, or renal replacement therapy. Urine output: stage 1 = under 0.5 mL/kg/h for 6-12 h, stage 2 = under 0.5 mL/kg/h for 12 h or more or under 0.3 for 12-24 h, stage 3 = under 0.3 mL/kg/h for 24 h or more. Any renal replacement therapy is automatically stage 3.
Baseline serum creatinine in mg/dL, used as the denominator for the creatinine ratio.
Current serum creatinine in mg/dL, compared with baseline or to the absolute 4.0 mg/dL threshold.
Body weight in kg, used with the urine output rate to assess urine-output criteria.
Urine output rate in mL/kg/h, compared with the 0.5 and 0.3 thresholds.
Duration in hours that the urine output rate has been low, determining the urine-output stage.
Yes automatically assigns stage 3 regardless of creatinine or urine output.
Stage 0: No AKI. Stage 1: Cr rise ≥0.3 mg/dL or 1.5–1.9× baseline; UO <0.5 mL/kg/h for 6–12h. Stage 2: Cr 2.0–2.9× baseline; UO <0.5 mL/kg/h for ≥12h. Stage 3: Cr ≥3.0× baseline or ≥4.0 mg/dL or RRT; UO <0.3 mL/kg/h for ≥24h.
The KDIGO 2012 guidelines define AKI using serum creatinine and urine output criteria. AKI is staged 1–3 based on severity. The highest applicable stage from either criterion is assigned. KDIGO staging is the current international standard for AKI classification.
A patient's baseline creatinine was 1.0 mg/dL; current creatinine is 2.5 mg/dL.
Inputs:
Expected Result: Ratio = 2.5/1.0 = 2.5× baseline → KDIGO Stage 2 AKI. Consider urgent nephrology consultation and renal ultrasound.
KDIGO AKI staging is an international classification system for acute kidney injury severity. It uses serum creatinine changes and urine output measurements to assign stages 1–3, with Stage 3 being the most severe.
The highest applicable stage is assigned. For example, if creatinine criteria meet Stage 1 but urine output criteria meet Stage 2, the final stage is Stage 2.
If no baseline creatinine is available, use the lowest creatinine value from the preceding 7 days, or estimate baseline using the MDRD or CKD-EPI equation assuming normal kidney function. Clinical judgment is essential.
No. KDIGO staging classifies severity but does not distinguish between prerenal, intrarenal (structural), or postrenal causes. The underlying etiology must be determined separately.
KDIGO is the most current standard (2012) and incorporates elements of both RIFLE (2004) and AKIN (2007). KDIGO uses both creatinine and urine output criteria, defines AKI based on changes within 48 hours or 7 days, and is the recommended classification in current clinical practice.
Disclaimer: This calculator is intended for educational and clinical decision support purposes only. KDIGO staging should be used in conjunction with clinical assessment and is not a standalone diagnostic tool.
Current international standard for AKI staging and severity classification.
Does not distinguish prerenal vs. intrarenal vs. postrenal causes.
Estimating chronic GFR for CKD staging and monitoring.
For chronic kidney disease, not acute kidney injury staging.
Differentiating prerenal azotemia from ATN in AKI.
Does not stage AKI; assesses etiology of established AKI.