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Learning Objectives
Understand normal kidney aging.
Classify kidney disease using the estimated glomerular filtration rate (eGFR).
Recognize environmental factors that impact the rate of decline in kidney function.
Recognize that genetic factors play a role in the age-related decline of kidney function.
Understand the general guidelines for managing patients with chronic kidney disease (CKD).
Understand the implications of aging on organ donation and receiving an organ transplant.
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Key Clinical Points
All older adults have some decline in renal function.
Older patients can typically maintain normal physiologic homeostasis but are compromised in their ability to respond to challenges.
Kidneys become more susceptible to injury with advancing age.
Rates of decline in renal function in aging are quite variable and impacted by genetic and environmental factors.
Preventing people from reaching end-stage renal disease reduces care costs and dramatically improves the quality of life.
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Data on individuals reaching end-stage kidney disease (ESKD) are collected by the US Renal Data System (USRDS). As a condition for coverage, all dialysis units receiving Medicare funding must file data with the Centers for Medicare and Medicaid Services (CMS). The 2020 USRDS annual data report shows that approximately 1.27 in 1000 persons aged 65 to 69 initiate treatment for ESKD each year. For the 70- to 75-year-old age group, the incidence rate of ESKD is 1.43 per 1000 persons, and this incidence peaks in the 80 to 84 age group to 1.82 per 1000. Over the last 10 years, the number of older individuals receiving renal replacement therapy has increased by 35% in those 75 years or older and by 43% in those older than 80 years. In contrast, the incidence of ESKD in the 20- to 44-year-old age group has remained flat over the last 10 years, with only modest growth in the 45- to 64-year-old age group. Although some of the increase in renal replacement therapy for the older population indicates a greater willingness to offer treatment to older individuals, much of the growth is owing to people surviving to experience the chronic changes that occur with aging. The kidney undergoes significant age-related change. Other common, age-related diseases such as hypertension and diabetes accelerate these changes.
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Aging in the kidney is characterized by changes in both structure and function. It must be emphasized that many of the aging studies have been performed on laboratory animals, particularly rodents, demonstrate quite different patterns of aging from humans. For example, kidney weight increases throughout life in rats, while kidney mass and size in humans peak in the fourth decade and decline thereafter. Care should be taken when reading the literature to keep in mind that changes observed in animal models may not reflect parallel changes seen in humans. Historical data from human postmortems describing changes in the kidney made no effort to exclude patients with ...