Aging & Health A to Z
Basic Facts & Information
The kidneys are two bean-shaped organs found in your lower back. Their function is to filter waste products produced by normal processes (for example, protein breakdown), to maintain the balance of acids and bases and many other chemicals (such as electrolytes) in your blood and tissues, and to eliminate byproducts of foods or medicines that your body does not need. The kidneys also help maintain body fluids at normal levels. In addition, the kidneys play important roles in controlling blood pressure and the production of red blood cells.
What are Kidney Diseases?
For about one-third of older people, kidney (also called renal) function remains steady throughout life. But for the rest of us, kidney function gradually starts to decline around age 35, sometimes worsening quickly in later years with increasing structural and hormonal changes. Our kidneys are normally more than capable of meeting the body’s demands, so there is a built-in reserve of kidney function, even as we age. Older kidneys, however, may not be as resilient as younger ones if they have been stressed. The result may be a higher risk of fluid imbalances, build-up of waste products, and other serious consequences in later years. Doses of medications must also be reduced if kidney function has declined, since your body can accumulate “overdose” levels if your kidneys cannot get rid of drugs efficiently.
The basic working components of each kidney is a structure called a nephron. Healthcare profesionals who specialize in the care of people with kidney (renal) diseases are called nephrologists.
The Most Common Types of Kidney Diseases
If your kidneys are not working well, you may eventually develop problems requiring medical attention. These problems from kidney disease may include:
- Fluid and electrolyte imbalance – e.g., too much or too little sodium, potassium, or water in your body
- Build up of waste products in your body
- Loss of protein through your kidneys
- High blood pressure from too much fluid in your body
- Anemia, or low blood counts
- Brittle bones.
If these problems become severe enough or don't recover, you may end up needing dialysis (use of a machine to wash out your blood).
How Common are Kidney Diseases?
Electrolyte imbalances, such as sodium concentrations that are either too high or too low are found in about one-quarter of all older people arriving at the emergency department. Older patients in hospital are very likely to have abnormally low sodium levels; more than one in five residents of long-term care facilities have this problem. Fluid imbalances are also common in older people, leading to dehydration, swelling, or other harmful conditions.
Nephrotic syndrome is common in older people because of leaking the filtering capacity of your kidneys. Nephrotic syndrome occurs in various forms, which can be seen by examining a biopsy of your kidneys under a microscope, including
- Membranous nephropathy
- Minimal change syndrome
- Amyloidosis (special proteins that accumulate around blood vessels in the kidney)
- Glomerulonephritis (inflammation of the filtering structures).
More than half of people over age 65 with kidney disease suffer from membranous nephropathy, about one in five have “minimal change” syndrome, and 10% have amyloidosis. Another 18% are diagnosed with glomerulonephritis.
Renovascular disease is disease of the blood vessels that supply the kidneys and occurs mostly in older adults, especially in people with heart and circulatory diseases and those who smoke. Healthcare professionals have found this condition in 25% of patients who have a common heart investigation called an angiogram.
Acute (sudden) kidney failure is increasingly common in older people, occurring about twice as often as end-stage kidney disease, with as many as 200,000 cases annually in the US.
Chronic kidney disease afflicts more than 20 million adults in this country. It affects 35% of diabetes patients, and about 20% of adults with high blood pressure.
Chronic kidney disease is very common in older people. Slowing or preventing its progress is an important and attainable goal.
Your general care provider or kidney specialist (nephrologist) can help you control your kidney disease by devising the best medical and lifestyle approaches for your individual condition.
End-stage renal (kidney) disease (ESRD) is diagnosed in over 100,000 new patients each year in the US. Almost 600,000 people are currently being treated for ESRD. The incidence is highest in adults over the age of 65 years, and in African Americans and Hispanic Americans. Every year, almost 400,000 ESRD patients are maintained on dialysis, about 18,000 receive a kidney transplant, and close to 90,000 patients with ESRD die.
Updated: May 2012
Posted: May 2012