The kidneys filter the blood and help remove wastes and extra fluid from the body. The kidneys also help control the body’s chemical balance. The kidneys are part of the urinary system, which also includes the ureters, bladder, and urethra. Muscle changes in the reproductive system can affect bladder control. As you age, your kidneys and bladder change. This can affect their function.

Changes in the kidneys that occur with age:

• Amount of kidney tissue decreases.
• Number of filtering units (nephrons) decreases. Nephrons filter waste material from the blood.
• Blood vessels supplying the kidneys can become hardened. This causes the kidneys to filter blood more slowly.

Changes in the bladder:

• The bladder wall changes. The elastic tissue becomes tough and the bladder becomes less stretchy. The bladder cannot hold as much urine as before.
• The bladder muscles weaken.
• The urethra can become blocked. In women, this can be due to weakened muscles that cause the bladder or vagina to fall out of position (prolapse). In men, the urethra can become blocked by an enlarged prostate gland.

In a healthy aging person, kidney function remains normal. But illness, medicines, and other conditions can affect kidney function.