[Acute kidney injury is a common and serious condition. The clinical significance is great and probably underestimated].

Acute kidney injury, previously called acute renal failure, is very common in different health care settings. Acute kidney injury is strongly related to an increased risk of death, myocardial infarction, heart failure and dialysis-dependent chronic kidney disease. The established classification of acute kidney injury, KDIGO, uses changes in serum creatinine values, and/or urine output to define different stages (stages 1-3). Acute kidney injury stage 1 is defined as an increase in serum creatinine levels of 26 μmol/l, or an 1.5-2-fold increase in serum creatinine levels compared with baseline values, which often goes undetected. The aim of this review was to give an overview of the classification, epidemiology, and importance of acute kidney injury for prognosis in different clinical settings.