The influence of age on the renal response to water deprivation in man.

Alterations in urine concentrating ability with age were examined in 98 active community-dwelling volunteers (aged 20-79 years) who were free from evidence of diseases known to adversely affect renal function. There was a significant decrease in urine osmolality reached after 12 h dehydration with advancing age, which could not be correlated with the age-related decline in creatinine clearance. A significant age-related diminution in the ability to conserve solute was also observed. This inability to conserve solute may result in diminished medullary tonicity and impaired urinary concentrating ability.