[Effects of aging on kidney function and implications for medical practice].

PHYSIOLOGICAL AGING

Anatomical and physiological renal changes occur during normal aging in humans. These changes are different from the renal effects of many diseases frequently linked to aging and which require specific diagnosis, prevention and therapy. Renal aging varies from one patient to another or from one population to another. During common aging, anatomical changes are mild and physiological changes mainly affect glomerular filtration rate and water and salt metabolism regulation. IN THE ELDERLY: Glomerular filtration rate decreases slowly in healthy elderly people to reach 80 ml/mn at 80 years without any metabolic consequence. However, in old hospitalized patients, acute renal failure is frequent and occurs mainly during inflammatory or infectious disorders, dehydration or drug combinations enhancing regulation of glomerular filtration. Tubular function changes expose the elderly to increasing risk of dehydration which could be prevented in highly predictable situations such as gastrointestinal symptoms, poorly salted diets or anorexia. Estimation of the creatinine clearance is necessary whenever an acute medical events, mostly infectious diseases, occur in elderly people to adapt drugs doses to renal catabolism.