Urinary lithiasis (condition of having stones) may be related to infection, irritation, diet, or hormone imbalances that lead to an increased level of calcium in the blood. Most urinary stones, or calculi, are formed of calcium salts, but they may be composed of other materials as well. Causes of stone formation include dehydration, infection, abnormal pH of urine, urinary stasis, and metabolic imbalances. 

The stones generally form in the kidney and may move to the bladder. This results in great pain, termed renal colic, and obstruction that can promote infection and cause hydronephrosis (collection of urine in the renal pelvis). Because they are radiopaque, stones can usually be seen on simple radiographs of the abdomen. Stones may dissolve and pass out of the body on their own. If not, they may be removed surgically, in a lithotomy, or by using an endoscope. External shock waves are used to crush stones in the urinary tract in a procedure called extracorporeal (outside the body) shock wave lithotripsy (crushing of stones).

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