Phases of acute kidney injury: where you can intervene
Which statement about the phases of acute kidney injury is correct?
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A. The maintenance phase responds best to treatment, because the injury is already established
In the maintenance phase the injury is already established: treatment is supportive (fluids, electrolytes, dialysis) while the tubules regenerate, but it does not reverse it.
B. The initiation and extension phases are the window in which removing the cause and restoring perfusion can limit the injury, often before creatinine rises
Correct. This is why low IRIS grades, small creatinine changes, urine output and sediment matter: detecting injury in these phases allows action while established damage can still be prevented.
C. Azotaemia appears as soon as the injury starts, so creatinine is enough to detect it in time
Creatinine rises late and only once a substantial part of filtration has been lost. Creatinine within the reference range does not rule out ongoing injury.
D. No monitoring is needed in the recovery phase, because the kidney always returns to its previous function
Recovery may be accompanied by polyuria with water and potassium losses, and it often leaves chronic kidney disease: it requires follow-up.
lightbulb Key takeaway
Initiation: the insult (ischaemia, toxin) acts. Extension: hypoxia and inflammation spread the damage. Maintenance: stable low filtration, for days to weeks. Recovery: tubular regeneration, sometimes with polyuria. Act in the first two: remove nephrotoxins and correct hypoperfusion immediately.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.