Why do our kidneys get old?

The majority of the human population shows a decline in renal clearance with age and a loss of renal physiologic reserve. Kidneys are increasingly less able to deal with stressful challenges such as a salt or acid load. It is not clear what underlies this aging-related change and whether it is inevitable or can be modified in such a way as to preserve renal function throughout the life span. This is a very brief review of aging biology and how it might impact on renal aging.