Table of Contents
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Calcium Stones. About 70 - 90% of all kidney stones are made of calcium, usually combined with oxalate, or oxalic acid. A number of common vegetables, fruits, and grains contain oxalate.
About 6% of calcium stones are made of calcium phosphate (called brushite).
Uric Acid Stones. Uric acid is responsible for close to 10% of kidney stones. It is the breakdown product of purines, nitrogen compounds found in the body and in certain foods. Uric acid enters the bloodstream, and then passes primarily into the kidneys. From the kidneys, uric acid leaves the body in the urine. Often, uric acid stones occur with calcium stones.
Struvite Stones. Struvite stones are made of magnesium ammonium phosphate. They are almost always associated with certain urinary tract infections. Worldwide, they account for up to 30% of all kidney stones. In the United States, however, fewer than 15% of all stones are struvite. Most struvite stones occur in women. The rate of these stones may be declining in America, perhaps because of better control of urinary tract infections.
Cystine Stones. A build-up of the amino acid cystine, a building block of protein, causes 1% of kidney stones in adults and up to 8% of stones in children. The tendency to form these stones is inherited. Cystine stones grow rapidly and tend to recur. If not treated promptly, they can eventually lead to kidney failure.
Xanthine Stones. Other kidney stones are composed of xanthine, a nitrogen compound. These stones are extremely uncommon and usually occur as a result of a rare genetic disorder.
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Review Date: 06/08/2010
Reviewed By: Reviewed by: Harvey Simon, MD, Editor-in-Chief, Associate Professor
of Medicine, Harvard Medical School; Physician, Massachusetts
General Hospital. Also reviewed by David Zieve, MD, MHA, Medical
Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
