Measuring renal function in old age

Abstract

Accurate assessment of renal function is vital, especially in older individuals, as this is the population in which the greatest burden of chronic kidney disease (CKD) occurs. With ageing, the kidneys undergo a multitude of structural and functional changes. The age-related changes in the kidneys may be further complicated by concurrent pre-renal, renal and post-renal factors common in old age, such as hypertensive glomerulosclerosis, diabetic nephropathy, congestive cardiac failure, renovascular atheroma, urinary outflow obstruction, urinary tract infections, renal stones and drug-induced nephrotoxicity. Structurally, there is a progressive loss of predominantly cortical renal mass, a decrease in the number of glomeruli, an increase in the proportion of sclerotic glomeruli, tubulo-interstitial changes resulting in fibrosis and atrophy, arteriosclerotic vascular changes and a reduction in renal blood flow. Excretory and reabsorptive capacities of the renal tubules may also decline with ageing. Functionally, although there may be a decline in the glomerular filtration rate (GFR) resulting primarily from a reduction in the number of functioning nephrons, this decline may not be universal. Up to a third of elderly people may not demonstrate a decline in GFR with ageing, whilst in some individuals GFR may actually increase with age.