[Renal function and aging]

Aging is associated with structural changes and modifications in renal function occurring as a consequence of a decrease in the number of functioning nephrons. Glomerular filtration decreases with age at a rate of 0.8 ml/min/year, starting at the fourth decade of life. In addition, renal adaptation to dietary sodium restriction as well as sodium loading are impaired during the aging process. Changes in renal tubular function include the regulation of potassium excretion resulting in a relatively high incidence of hyperkalemia, spontaneously or facilitated by treatments known to produce potassium retention. Practical consequences of renal aging, specially adaptation of doses of medications with preferential renal elimination, are analyzed.