The Urinary System

Urinary System Problems, Diseases & Conditions

The urinary tract at a glance

  • The urinary tract is the organ system that filters circulating blood to keep a proper balance of water and electrolytes.
  • Blood is filtered through the kidney, where the blood is processed. The waste byproduct is called urine, which moves from the kidney, through the ureters and ultimately is stored in the bladder until it is expelled through urination.
  • Common conditions of the urinary tract include urinary tract infections (UTIs), kidney stones, interstitial cystitis (painful bladder syndrome), and prostatitis (infection or inflammation of the prostate gland in men).
  • Among cancers of the urinary tract, prostate cancer is the most common but also highly survivable.

How does the urinary tract work?

The job of the urinary tract – also known as the urological system or renal system – is to produce and drain urine. Urine is made up of waste and unneeded fluids that have been filtered from the blood. The overarching goal of the urinary tract is to work in concert with the skin, intestines and lungs to keep a balance of water and chemicals in the body.

Most people produce about one quart to multiple quarts of urine each day. The amount varies depending on each person’s general health, weight and level of activity, as well as surrounding temperature and humidity. With higher humidity and temperature, the body expels less of its fluids through urination and more through perspiration.

The urination process begins with the kidneys, which filter from 120 to 150 quarts of blood daily. Each kidney is about the size of a fist and shaped like a large bean. The kidneys lie just below the rib cage and on both sides of the spine.

The kidneys pass urine to the bladder through a thin, muscular tube called the ureter. The bladder, located between the pelvic bones a little below the level of the belly button, is shaped like a balloon and expands and contracts as needed. In a normal person it holds about one-and-a-half to two cups of urine.

Whereas the kidneys work around the clock, we do have control over the bladder. This is because as the bladder fills, it sends messages to the brain, alerting us of a need to urinate.

During urination, the bladder empties urine through another tube called the urethra, located at the bottom of the bladder. The muscles of the bladder are then relaxed as it refills for another cycle.

What kinds of doctors treat urological problems?

Generally, urologists are the specialists who treat problems in the kidneys, bladder, ureter and urethra in men, women and children. Urologists also handle problems with men’s reproductive health, while gynecologists specialize in the female reproductive tract.

Nephrologists are specialists who focus on more complex kidney diseases. Sometimes oncologists (cancer doctors) and endocrinologists (specialists in the hormone system) also work with urologists and nephrologists.

Common urinary tract conditions

Urinary tract infections (UTIs) are caused by bacteria affecting the ureter, bladder, urethra and sometimes the kidneys. These infections are most common in women, although they do affect men as well.

Kidney stones occur when chemicals normally found in the urine form crystals that then build to solid structures. Kidney stones generally form in the kidney. When they pass into the ureter they can cause severe pain (renal colic) or blood in the urine. When significant blockage occurs, infection or kidney failure can result.

There are multiple potential causes of kidney stones including dehydration, dietary influences and abnormal kidney excretion of certain chemicals. When kidney stones cause pain or obstruction, there are surgical procedures that can be used to break or remove the stone(s).

Interstitial cystitis is a chronic bladder condition primarily in women. Also known as painful bladder syndrome, it can cause bladder pressure and pain that sometimes extends throughout the pelvis.

Prostatitis is swelling of the prostate gland in men. The swelling can be due to infection or non-infectious causes. Symptoms include pain during urination, the need to urinate frequently, pain in the scrotum or anal area, and fever.


Cancers of the urinary tract

Kidney cancer

Kidney cancer is relatively uncommon, but can be problematic because there are usually no symptoms in its early stages. Men are twice as likely to develop kidney cancer than women. Compared to some other forms of cancer, the survival rate for kidney cancer can be favorable – the five- and ten-year rates are 72 percent and 62 percent, according to the American Cancer Society.

When symptoms of kidney cancer do appear, they may include:

  • Blood in the urine
  • Weight loss
  • Fatigue
  • A pain or lump in the lower back
  • Swelling in the ankles and legs.

Risk factors include smoking, obesity, high blood pressure, and exposure to certain chemicals and radiation.

Bladder cancer

Bladder cancer affects men three to four times more often than women. It occurs principally in older people, with the average age at time of diagnosis being 73. The risk of a man getting bladder cancer in his lifetime is 3.83 percent, compared to about a 15 percent chance of getting prostate cancer. The odds of surviving bladder cancer can be as high as 96 percent five years after diagnosis if the tumor is found before it spreads. The most common symptom is blood in the urine.

Prostate cancer

Prostate cancer is the second most common cancer diagnosed in men, after skin cancer, and the second leading cause of cancer deaths in the United States, after lung cancer. According to the American Cancer Society, an estimated 220,800 new cases of prostate cancer occur annually, and nearly 28,000 Americans die from this disease annually.

Like cancer of the kidney, prostate cancer usually is asymptomatic (shows no symptoms) in its early stages. In later stages, symptoms may include:

  • A weak urine flow
  • Pain or burning during urination
  • Difficulty starting or stopping urination
  • Blood in the urine
  • The need to urinate frequently.

More than half of prostate cancer cases are diagnosed in men at least 65 years of age, and 97 percent of all cases are in men 50 and older. Rates of the disease are about 60 percent higher in men of African ancestry.

The American Cancer Society reports that since 1990 the five-year relative survival rate for all stages of prostate cancer has increased from 68 percent to almost 100 percent, in part due to early detection using PSA screening.