How Does a Kidney Stone Develop?

About Kidney Stones

The kidneys produce urine by filtering minerals and metabolites from the circulatory system. Normally, these minerals simply dissolve in the urine, but they can sometimes crystalize and aggregate to form a solid mass that attaches to the kidney wall. Kidney stones can be microscopic, or as large as a golf ball. Disorders of the kidney and Crohn's disease can increase your risk for kidney stones. Dehydration can also cause kidney stones, as their is a higher probability that the mineral will separate from the urine in the urinary tract.

Calcium Oxalate Stones

Calcium oxalate is a chemical compound made up of calcium, carbon and oxygen. It forms needle-shaped crystals, and is responsible for about 80 percent of kidney stones. While it was formerly thought that a low-calcium diet might inhibit the formation of these stones, the reverse appears to be true. Calcium binds to oxalate in the digestive tract, meaning that there is less oxalate available to be absorbed into the bloodstream. Less calcium means more oxalate is filtered by the kidneys, and it may then bind with calcium in the urinary tract, causing kidney stones. Oxalate naturally occurs in high amounts in some foods, such as chocolate, sweet potatoes, spinach and beets.

Struvite and Uric Acid Stones

Struvite stones form due to urinary tract infections. Certain bacteria can convert urea into ammonia, reducing the acidity of the urine and allowing magnesium, phosphate and ammonium to crystalize and form struvite stones. Proteus mirabilis is a bacteria that commonly leads to struvite stones. But high amounts of uric acid can also cause kidney stones. If the kidneys must filter excessive amounts of uric acid from the bloodstream, it may crystalize in the urinary tract. About 5 to 10 percent of kidney stones are uric acid stones and they usually occur in people with underlying conditions such as gout or metabolic disorders.

Resources

• National Kidney and Urologic Diseases Information Clearinghouse