What are kidney stones made of?
Kidney stones consist of a center that consists of crystal-like substances, and a surrounding region that is composed of layers. Kidney stones are composed of different chemical substances. Each of the major types is named for its main chemical ingredient. They are calcium stones, uric acid stones, cystine stones, and struvite stones.
Calcium stones are the most common type of kidney stones, accounting for 75 to 85 percent of all stones. Most of these stones consist of calcium oxalate, or a combination of calcium oxalate and phosphate. Their formation is linked to high levels of urinary calcium, or a combination of calcium and uric acid, in the urine.
Uric acid stones are relatively uncommon, accounting for 5 to 8 percent of all stones. A high level of uric acid in the blood and urine can cause this type of stone. They can form if a person's urine becomes concentrated with certain dissolved substances that may make it more acidic.
Cystine stones are rare, accounting for less than one percent of all kidney stones. These stones result from an inherited condition that causes an increase in the amount of cystine (an amino acid) in the urine. Because cystine cannot dissolve easily in water, it cannot be reabsorbed from the urine into the blood. This increases the chances that a stone will form.
Struvite stones make up 10 to 15 percent of all kidney stones. Because these stones can be quite large, they can cause serious symptoms. Struvite stones are formed because of infection by specific bacteria, which throws off the balance of acid in the urine. These stones are mainly composed of ammonium and magnesium phosphate and resemble hard crystals.
More information on kidney stones
What are kidney stones? - Kidney stones are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. Also known as nephrolithiasis, urolithiasis or renal calculi.
What are kidney stones made of? - Kidney stones consist of a center that consists of crystal-like substances, and a surrounding region that is composed of layers. Kidney stones are composed of different chemical substances.
What are the symptoms of kidney stones? - Symptoms often occur when a stone migrates into the ureter, the tube that carries urine from the kidney to the bladder, and prevents the drainage of urine from the kidney.
What causes kidney stones? - The development of the stones is related to decreased urine volume or increased excretion of stone-forming components such as calcium, oxalate, urate, cystine, xanthine, and phosphate.
What are the risk factors for kidney stones? - Kidney stones affect about 12% of men and 5% of women by the time they are 70 years old. Kidney stones that strike women are more apt to occur during pregnancy.
How are kidney stones diagnosed? - Diagnosis of renal stone disease involves a medical history, physical examination, laboratory evaluation, and imaging tests.
What're treatment options for kidney stones? - Treatments of kidney stones include dietary modifications (including the advice to drink plenty of water), medications, and use of a lithotriptor.
What drug treatments are available for treatment and prevention of kidney stones? - Diuretics are commonly used in the treatment of high blood pressure and other disorders to eliminate fluid and sodium from the body. Citrate salts are often given to people with calcium oxalate or uric acid stones.
What dietary factors and lifestyle measures are used for prevention of kidney stones? - The most important recommendations for reducing the risk for calcium stones are increasing fluid intake, restricting sodium, and reducing protein intake.