Structural and Functional Changes With the Aging Kidney

Abstract

Senescence or normal physiologic aging portrays the expected age-related changes in the kidney as compared to a disease that occurs in some but not all individuals. The micro-anatomical structural changes of the kidney with older age include a decreased number of functional glomeruli from an increased prevalence of nephrosclerosis (arteriosclerosis, glomerulosclerosis, and tubular atrophy with interstitial fibrosis), and to some extent, compensatory hypertrophy of remaining nephrons. Among the macro-anatomical structural changes, older age associates with smaller cortical volume, larger medullary volume until middle age, and larger and more numerous renal cysts. Among carefully-screened healthy kidney donors, glomerular filtration rate declines at a rate of 6.3 ml/min/1.73m2 per decade. There is reason to be concerned that the elderly are being misdiagnosed with chronic kidney disease. Besides this expected kidney function decline, the lowest risk of mortality is at a glomerular filtration rate of ≥75 ml/min/1.73 m2 for age <55 years but at a lower glomerular filtration rate of 45-104 ml/min/1.73m2 for age ≥65 years. Changes with normal aging are still of clinical significance. The elderly have less renal functional reserve when they do actually develop chronic kidney disease and they are also at higher risk for acute kidney injury.

Single-Nephron Glomerular Filtration Rate in Healthy Adults

“…The apparent failure of the single-nephron GFR to increase with the expected age-related nephron loss, whereas it increased with nephro-sclerosis beyond the level expected for age, may support an age-based approach to the identification of chronic kidney disease. 25 Previous studies have linked larger nephrons to a higher single-nephron GFR in an animal model, 26 and the present study extends this finding to humans. In studies in animals, surgical renal ablation leads to a higher glomerular pressure and blood flow, which drives increases in both glomerular size and single-nephron GFR.…”

Current Understanding of the Pathogenesis of Progressive Chronic Kidney Disease in Cats

“…It can therefore be debated whether a diagnosis of CKD in the elderly truly represents a disease process rather than part of normal ageing. [10][11][12][13] Although CKD is most often identified in cats over the age of 12 years, there is evidence that tubulointerstitial inflammation may be identified in the renal parenchyma of young cats that have died for other reasons and as such it has been proposed that the development of CKD may also be part of a normal aging process in cats. 14 Ageing is a programmed biological process, which is regulated by many genes.…”

Recuperação De Pacientes Com Lesão Renal Aguda Dialítica E Não Dialítica

“…As mudanças estruturais microanatômicas do rim com a idade mais avançada incluem a redução do número de glomérulos funcionais em decorrência do aumento da prevalência da nefroesclerose (arteriosclerose, esclerose glomerular, atrofia tubular e a fibrose intersticial), e, em certa medida, pela hipertrofia compensatória de néfrons remanescentes (18) . Nesse contexto, a idade avançada representa um fator predisponente à ocorrência da LRA.…”