NEPHROLOGY - REVIEW Acute kidney injury in the elderly population Rahmi Yılmaz Æ Yunus Erdem Received: 7 January 2009 / Accepted: 29 July 2009 / Published online: 26 August 2009 Ó Springer Science+Business Media, B.V. 2009 Abstract The elderly population is more prone to acute kidney injury (AKI) than younger populations. Older patients have less renal reserve because of reduced glomerular filtration rates due to anatomic/ functional changes, and concomitant diseases such as hypertension, diabetes, atherosclerosis, heart failure, ischemic renal disease, and obstructive uropathy. The risk of AKI may also increase as a result of aggressive diagnostic and therapeutic procedures, which include medical agents, radiology, and surgical intervention. AKI in the elderly has a multifactorial physiopathology due to different etiologies. Studies that have specifically compared prognosis of AKI in elderly versus young over the recent years suggest that age is a predictor of long-term outcome. In most cases, the treatment of AKI is similar for all age groups. The majority of critically ill patients with AKI will eventually need renal replacement therapy (RRT). The influence of RRT on renal outcome remains a subject of intense investigation and debate. Avoiding situations that could damage the kidney is an important strategy to prevent AKI development in the elderly, besides medical and interventional therapeutics. Keywords Acute kidney injury Á Ageing of kidney Á Elderly population Á Prevention Á Prognosis Á Renal recovery Á Renal replacement therapy Introduction Global life expectancy at any age has increased in the developed world. Demographic projections predict a major increase in the population above 65 years old [1]. Simultaneously, the number of elderly patients with acute kidney injury (AKI) has also increased. There are many medical reasons that explain this rise in AKI among elderly patients. First, age is associated with many structural and functional changes that lead to diminished nephron reserve and reduced capacity of renal autoregulation [2]. Second, increased long- term life expectancy results in larger numbers of people with chronic diseases such as hypertension, diabetes mellitus, and cardiovascular diseases that may cause renal damage. Third, the elderly popula- tion uses many medications, including nephrotoxic agents. Because of the decrease in renal function associated with increasing age, the dosage of renally excreted drugs should be reduced. Together, these factors represent the additional risks for the develop- ment of AKI in the elderly population [3]. Since the early 1990s, acute renal failure was defined as a sudden (hours to weeks) decline in R. Yılmaz Á Y. Erdem (&) School of Medicine, Nephrology Department, Hacettepe University, 06100 Ankara, Turkey e-mail: yerdem@hacettepe.edu.tr 123 Int Urol Nephrol (2010) 42:259–271 DOI 10.1007/s11255-009-9629-7