Pathophysiology of ischaemic acute kidney injury

Acute kidney injury is common, dangerous and costly, affecting around one in five patients emergency admissions to hospital. Although survival decreases as disease worsens, it is now apparent that even modest degrees of dysfunction are not only associated with higher mortality but are an independent risk factor for death. This review focuses on the pathophysiology of acute kidney injury secondary to ischaemia - its commonest aetiology. The haemodynamic disturbances, endothelial injury, epithelial cell injury and immunological mechanisms underpinning its initiation and extension will be discussed along with the considerable and complex interplay between these factors that lead to an intense, pro-inflammatory state. Mechanisms of tubular recovery will be discussed but also the pathophysiology of abnormal repair with its direct consequences for long-term renal function. Finally, the concept of 'organ cross-talk' will be introduced as a potential explanation for the higher mortality observed with acute kidney injury that might be deemed modest in conventional biochemical terms.