Chapter 18: Acute Kidney Injury in the Elderly

Acute kidney injury (AKI), as defined by the precipitous decline in GFR, is frequently encountered in the elderly. The effect of advancing age in decreasing renal reserve and the associated comorbid conditions of elderly patients increase the risk for the development of AKI. Although studies describing the incidence of AKI in this population are difficult to compare because the definitions of AKI vary dramatically from study to study, it is clear that the elderly are at the highest risk for the development of AKI. Indeed, Feest et al.1 showed that there is a threeto eight-fold, progressive, age-dependent increase in the frequency of development of community-acquired AKI in patients older than 60 yr of age. The mean age of patients with AKI has increased by 5 to 15 yr over the past 25 yr.2 Groeneveld et al.3 showed that the age-related yearly incidence of AKI rose from 17 per million in adults under age 50 yr to 949 per million in the 80 to 89 yr age group. Although all causes of AKI are encountered in this age group, the frequency of prerenal and postrenal etiologies is especially prevalent in the elderly.4 Furthermore, elderly patients are more frequently subjected to invasive procedures and exposure to multiple (and possibly nephrotoxic) medications and to radiocontrast agents, all of which increase the risk for AKI.