What causes kidney stones?
Kidney stones are hardened crystal clumps that can develop in the urinary system. They usually form because there is a breakdown in the balance of liquids and dissolved solids in the urine. The kidneys must keep the right amount of water in the body while they remove materials that the body cannot use. If this balance is disturbed, the urine can become overloaded with substances (usually small crystals) that won’t dissolve in water. Crystals begin to stick together and slowly add layer upon layer to form a stone. A kidney stone may grow for months or even years before it causes a problem. Experts suggest that age, diet, climate, infection and inherited disorders are some possible causes of kidney stones.
Doctors do not always know what causes a stone to form. It seems that some people are just susceptible to having stones—and those who are might increase their risk by eating certain foods, or by not drinking enough water. A person with a family history of kidney stones may be more likely to develop stones. Urinary tract infections, kidney disorders such as cystic kidney diseases, and metabolic disorders such as hyperparathyroidism are also linked to stone formation. Certain intestinal disorders can increase the risk, as can taking certain medications, like protease inhibitors. Even taking diuretics or calcium-based antacids can increase the risk of forming stones.
Kidney stones form when there is a decrease in urine volume and/or an excess of stone-forming substances in the urine. The most common type of kidney stone contains calcium in combination with either oxalate or phosphate. Other chemical compounds that can form stones in the urinary tract include uric acid and the amino acid cystine. Dehydration from reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones. Obstruction to the flow of urine can also lead to stone formation. Kidney stones can also result from infection in the urinary tract; these are known as struvite or infection stones. Men are especially likely to develop kidney stones, and Caucasians are more often affected than blacks. The prevalence of kidney stones begins to rise when men reach their 40s, and it continues to climb into their 70s. People who have already had more than one kidney stone are prone to develop more stones. A family history of kidney stones is also
