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AKI Stage Based on SCr AKI Stage Based on UO Assumptions
AKI Calculator is an automated version of the guidelines for staging AKI using RIFLE, AKIN, and KDIGO. These guidelines give two staging scores based on:
All three guidelines (RIFLE, AKIN, and KDIGO) have identical criteria for calculating UO based risk scores. However, each guideline differs slightly in the SCr based risk scores. These differences may be seen by toggling the displayed guideline on the website. For more details on the guidelines and equations, see the References.
AKI Calculator displays the maximum of the two stages between:

AKI Stage Based on SCr
AKI stage based on SCr is determined by evaluating SCr relative to a baseline SCr. If no baseline value is known, it is computed via the MDRD formula. AKI stage by SCr may use initiation of dialysis and evaluation of estimated glomerular filtration rate (eGFR) relative to baseline eGFR during calculation. The higher the SCr above the baseline (or lower eGFR below baseline), the higher the AKI stage.

AKI Stage Based on UO
AKI stage based on UO is determined by evaluating urine output normalized by body weight over time relative to a threshold/nominal value. Catheter insertion time is required to establish a starting time. UO entered in the input tab of the AKI Calculator must be at least 6 hours after the catheter insertion time to receive an AKI stage (score). The lower the UO below the threshold, the higher the AKI stage.

Assumptions For All Guidelines
Additional KDIGO Assumptions
Additional AKIN and KDIGO Assumptions
Additional RIFLE Assumptions
Additional MDRD Assumptions