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Kidney & Ureteral Stones

Stone disease is among the most painful and prevalent urological disorders.  More than a million kidney stone cases are diagnosed each year with an estimated 10 percent of Americans destined to suffer from kidney stones at some point in their lives.

The incidence of urolithiasis, or stone disease, is about 12% by age 70 for males and 5-6% for females in the United States.  Additionally, the gender gap may be decreasing as more women are being diagnosed and treated for kidney stones.  The reason for the change is of the dietary and climate changes in our population.  The debilitating effects of kidney stones is quite substantial, with patients incurring billions of dollars in treatment costs each year.

Fortunately, most stones pass out of the body without any intervention. If you are not so lucky, the following information should help you and your doctor address the causes, symptoms and possible complications created by your kidney stone disease.

What are stones and the difference between kidney stones and ureteral stones?

Normally, urine contains many dissolved substances. At times, some materials may become concentrated in the urine and form solid crystals. These crystals can lead to the development of stones when materials continue to build up around them, much as a pearl is formed in an oyster. 

Stones formed in the kidney are called kidney stones.  Ureteral stone is a kidney stone that has left the kidney and moved down into the ureter.

The majority of stones contain calcium, with most of it being comprised of a material called calcium oxalate. Other types of stones include substances such as calcium phosphate, uric acid, cystine and struvite.

Stones form when there is an imbalance between certain chemical urinary components such as calcium, oxalate and phosphate.  These chemical components either promote crystallization while others inhibit it.

The most common stones contain calcium in combination with oxalate and/or phosphate.

A less common type of stone is caused by infection in the urinary tract. This type of stone is called a struvite or infection stone. Much less common are the pure uric acid stones. Much rarer is the hereditary type of stones called cystine stones and even more rare are those linked to other hereditary disorders.

What happens under normal conditions?

The urinary tract, or system, consists of the kidneys, ureters, bladder and urethra. The kidneys are two bean-shaped organs below the ribs in the back of the torso (area between ribs and hips). They are responsible for maintaining fluid and electrolyte balance by removing extra water and wastes from the blood and converting it to urine.

The kidneys keep a stable balance of salts and other substances in the blood. They also produce hormones that build strong bones and help form red blood cells. Urine is carried by narrow muscular tubes to the ureters, from the kidneys to the bladder, a triangular-shaped reservoir in the lower abdomen. Like a balloon, the bladder's walls stretch and expand to store urine and then flatten when urine is emptied through the urethra to outside the body.  Normally, urine contains chemicals that prevent crystals from forming.

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Information provided by the American Urological Association.