A review of the pathophysiology, causes and prognosis of acute renal failure in the elderly

Acute kidney injury in the elderly: pathogenesis, diagnosis and therapy

Elderly patients, especially those with chronic kidney disease, are at least a 3.5-fold higher risk for the development of acute kidney injury (AKI). With aging, renal functional reserve is lower owing to specific cellular changes that affect function. Molecular studies are elucidating these cellular changes and offer the prospect of designing novel therapeutics. The spectrum of AKI in elderly patients is wide but is over-represented by prerenal and postrenal (obstructive) etiologies. This reflects potentially nephrotoxic clinical variables, such as combordid states, impaired baseline renal function, polypharmacy and an increase in high-risk procedures. In this population, the development of AKI can lead to longer hospital stays, higher mortality rates and an increased risk for the development of chronic kidney disease and end-stage renal disease. Careful attention to clinical risk factors, avoidance of nephrotoxic insults and meticulous supportive care for patients who develop AKI is critical in alleviating the burden of this problem.

Renal function and renal disease in the elderly: Part I

In all industrialized countries, life expectancy has risen in the past 100 years. The incidence of elderly patients reaching end-stage renal disease (ESRD) and requiring renal replacement therapy has also increased. During the past few decades, the pattern of ESRD has changed significantly with the emerging predominance of elderly patients. The causes of this phenomenon are manifold and include an increasing number of chronic diseases typical of the 'third age', such as type 2 diabetes mellitus and vascular disease. In many species, a consequence of aging includes deterioration of renal function, partly due to structural alterations, and partly as the result of a diminishing blood flow. In humans, the aging kidney is characterized by modifications resulting from organic and functional disturbances. In particular, type 2 diabetes mellitus has emerged as an important condition, the microvascular and macrovascular complications of which are a common cause of morbidity and mortality in older patients. In part I of this review, the morphological and functional changes of the aging kidney will be reviewed, as well as the pathological conditions leading to the loss of renal function in the elderly.

Variation of intrarenal angiotensin II and angiotensin II receptors by acute renal ischemia in the aged rat

The properties of Ang II receptors in the aged kidney and their changes after acute renal ischemia are rarely known. The aim of this study was to examine the expression of Ang II receptor mRNA and characteristics of Ang II receptors in the aged kidney and to compare different responsiveness to 45 min of acute renal ischemia in young (3-4 months) and aged (23-24 months) rats. In the normal condition, AT1 mRNA expression was much lower in the aged than that in the young rats. Maximal binding (Bmax) was also lower in the aged (1315 +/- 48 vs. 2035 +/- 257 fmol/mg, p < 0.05). The dissociation constant (KD) of glomerular Ang II receptors, however, was significantly lower in the aged rats compared to the young (6.8 +/- 1.6 vs. 17.4 +/- 2.5 nM). After acute ischemia, the expression of AT1 mRNA decreased in the young rats but increased in the aged rats. Interestingly, Bmax of glomerular Ang II receptors was significantly increased in the aged ischemic rats (1852 +/- 94 vs. 1315 +/- 48 fmol/mg) with unchanged KD. These results show that: (a) the AT1 mRNA expression and the Ang II receptor binding site are decreased with the aging process in the rat kidney; (b) the acute renal ischemia effect on different age groups has a greatly discrepant pattern in respect of Ang II receptor modulation, which may provide a potential therapeutic future for the receptor antagonists in acute renal ischemia in the aged.