Kidney and aging - A narrative review

The kidney undergoes age-related changes, reaching full functionality after the age of 5 years and suffering a slow but progressive decline in its regulatory range of function (e.g. matching sodium and potassium excretion to dietary intake), starting at the age of ~ 20 years, as well as in function (e.g. glomerular filtration) starting at a higher age. Age-related decline in renal function is also a matter of gender, race and genetic background. Pathogenetically, mediators of chronic inflammation, oxidative stress and the renin-angiotensin-aldosterone (RAAS) system are relevant factors determining renal aging, due to an enhanced incidence of cellular damage combined with reduced repair capacities. In addition cardiovascular diseases play a significant role. Features of renal aging include several functional alterations, like reduction of glomerular filtration rate, sodium reabsorption, potassium secretion, vitamin D3 synthesis, titratable acid excretion, responsiveness to hormones, and regulatory flexibility. Assessment of renal function has to account for age-related changes and is confronted with the challenge to differentiate between age-based physiological alterations and true pathological situations that require appropriate intervention.