BACKGROUND

The kidneys filter the blood and help remove waste and extra fluid from the body. The kidneys also play an important role in controlling the body's chemical balance. As with other organs, kidney function may be slightly reduced with aging.

The kidneys are part of the urinary system, which also includes the ureters and the bladder.

Bladder control can be affected by muscle changes and changes in the reproductive system.

AGING CHANGES

As the kidneys age, a number of events occur:

• The number of filtering units (nephrons) decreases. Nephrons filter waste material from the blood.
• The overall amount of kidney tissue also decreases.
• The blood vessels supplying the kidney can become hardened, and the kidneys filter blood more slowly.

Changes in the bladder:

• The bladder wall changes with age.
• The elastic tissue becomes tough, and the bladder becomes less stretchy.
• Muscles weaken, and the bladder may not empty completely when urinating.

In women, weakened muscles can allow the bladder or vagina to fall out of position (prolapse), which can block the urethra. In men, the urethra may become blocked by an enlarged prostate gland.

EFFECTS OF CHANGES

Under usual conditions, kidney function remains normal in an aging person. Although sometimes they kidneys may function more slowly than those of a younger person.

However, illness, medications, and other conditions can affect a kidney's ability to function properly. Changes in the kidneys may affect an elderly person's ability to concentrate urine and hold onto water. Dehydration occurs more readily because older people frequently have less of a sense of thirst.

Dehydration can also be aggravated if an older person reduces fluid intake in an attempt to reduce bladder control problems.

COMMON PROBLEMS

Aging increases the risk for urinary disorders, such as:

• Acute kidney failure
• Chronic kidney failure
• Bladder control issues (urinary incontinence, or leakage or urinary retention, which means you are not able to completely empty your bladder)
• Bladder infections
• Other urinary tract infections (UTIs)

UTIs are common, and partly due to incomplete emptying. It is also related to changes in the chemical balance in the urinary tract.

Urinary system cancers are more common in the elderly, especially prostate cancer (men) and bladder cancer.

In both men and women, urinary changes are closely related to changes in the reproductive system. For example, men may experience problems because of an enlarged prostate (benign prostatic hypertrophy). Women may have vaginal infections (vaginitis) and bladder infections.

The aging kidney is more susceptible to adverse drug events. For example, nonsteroidal anti-inflammatory drugs (NSAIDs) and heart medications called ACE inhibitors can cause acute kidney failure failure in some cases. It is important that routine lab tests are done when these medications are used.

See also:

• Aging changes in the bones, muscles, and joints
• Aging changes in the male reproductive system
• Aging changes in organs, tissues, and cells