Acute kidney injury

The kidneys maintain health by regulating water balance, electrolytes, acid base and regulate blood pressure. They also excrete metabolic waste/toxins and play a role in secretion and metabolism of hormones. An acute insult or injury to the kidneys can lead to cellular damage and necrosis. This in turn can result in alteration to the normal functions of the kidney. There can be an abrupt decline in glomerular filtration rate (GFR) characterised by increased serum/plasma creatinine concentration, uraemia (symptoms associated with increased urea and creatinine), and changes in urine output (Legatti et al, 2018) — this is known as acute kidney injury (AKI).

There are four phases of AKI pathophysiology (Monaghan et al, 2012):

There are numerous classification systems used in the literature for staging patients with AKI including: International Renal Interest Society (IRIS) guidelines (Table 1); Risk, In-jury, Failure, Loss and End-stage renal failure (RIFLE) consensus; Veterinary Acute Kidney Injury (VAKI) criteria and the Acute Kidney Injury Network (AKIN) system (Thoen and Kerl, 2011; Cowgill, 2016). These grading systems use a combination of blood creatinine and urine output (UOP) for staging the disease.