Acute Kidney Injury (AKI) Onset is very Sudden can take hours to days Usually a specific, often reversible trigger (e.g., dehydration, infection, obstruction, toxins, severe blood loss) 3 months (persistent loss of kidney function) Reversibility Sudden drop in urine output, shortness of breath Chronic Kidney Disease (CKD) Gradual take months to years Long-term conditions that damage kidneys over time (e.g., diabetes, high blood pressure, polycystic kidney disease)