Obesity, acute kidney injury and outcome of critical illness.

Acute kidney injury is a heterogeneous clinical syndrome encompassing a spectrum of risk factors and acute insults, occurring in multiple settings and affecting both short-term and long-term outcomes. Obesity has become an epidemic. The available literature suggests that AKI is common in critically ill surgical or medical obese patients and that obesity is a novel risk factor for this acute renal syndrome. The pathophysiology of obesity-associated AKI is not completely understood. Obesity-related factors combined with the burden of other comorbidities in elderly obese patients may interact with known precipitating factors such as hypotension, nephrotoxins or sepsis and increase the susceptibility of this population to AKI. Whether or not obesity may counterintuitively be protective and associated with better survival of critically ill patients with AKI ("reverse epidemiology") is a subject for debate. Further investigations exploring the role of novel biomarkers and optimal management are needed urgently.