Key Learning Points

1. 1. Acute kidney injury (AKI) is characterised by an acute decline in glomerular filtration rate, defined by an increase in serum creatinine and/or fall in urine output, according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria.

2. 2. Clinical risk scores, biomarkers and stress tests have been developed for prediction and risk stratification in AKI. Combining risk scores with biomarkers or stress tests can increase accuracy in AKI prediction and prognostication.

3. 3. Common causes of AKI in critically ill patients are hypovolaemia, sepsis, nephrotoxin exposure and haemodynamic instability, often in combination. Each cause has distinct and complex pathogenesis.

4. 4. General principles of AKI management are optimisation of haemodynamic and fluid status with appropriate monitoring, serial measurement of creatinine and electrolytes, urine output monitoring, glucose control, avoidance of nephrotoxic drugs, treatment of the underlying cause, management of potential AKI-related complications and renal replacement therapy if indicated.

5. 5. AKI is associated with short- and long-term complications, premature chronic kidney disease and end-stage renal disease and death. Monitoring of AKI survivors is essential.