== Mechanism of Acute Kidney Injury ==

Acute kidney injury (AKI), also known as acute renal failure (ARF), is characterized by an abrupt decline in renal function, leading to a reduction in the glomerular filtration rate (GFR) and the subsequent accumulation of nitrogenous waste products in the body.<ref name = "Ref15"> Lote, C.J., Harper, L. and Savage, C.O. (1996) ‘Mechanisms of acute renal failure’, British Journal of Anaesthesia, 77(1), pp. 82–89. doi:10.1093/bja/77.1.82.</ref> The clinical signs of acute kidney injury (AKI) are characterized by either an elevation in serum creatinine levels, a decrease in urine output, or both.<ref name = "Ref16">Ronco, C., Bellomo, R. and Kellum, J.A. (2019) ‘Acute kidney injury’, The Lancet, 394(10212), pp. 1949–1964. doi:10.1016/s0140-6736(19)32563-2

Pre-renal kidney failure is a term used to describe the condition in which there is a systemic circulation disorder leading to a reduction in renal perfusion and subsequently a reduction in GFR. <ref name = "Ref17"> Kellum, J.A. and Lameire, N. (2013) ‘Diagnosis, evaluation, and management of Acute Kidney Injury: A KDIGO summary (part 1)’, Critical Care, 17(1), p. 204. doi:10.1186/cc11454. </ref> Notable causes that can contribute to pre-renal kidney failure include reduced blood volume, peripheral vasodilation, reduced arterial pressure or impaired cardiac function, leading to a reduced cardiac output. <ref name = "Ref17"/> Characterising a condition as pre-renal implies that addressing the root cause of the circulatory disorder, by improving cardiac function or replenishing lost volume, may lead to the restoration of GFR. <ref name = "Ref16"/> However, in most cases, pre-renal failure is often followed by intrinsic renal failure where the GFR of a patient may not be restored, despite addressing pre-renal causes.