Urinary tract stones begin to form in a kidney and may enlarge in a ureter or the bladder. Depending on where a stone is located, it may be called a kidney stone, ureteral stone, or bladder stone. The process of stone formation is called urolithiasis, renal lithiasis, or nephrolithiasis.
Every year, about 1 of 1,000 adults in the United States is hospitalized because of stones in the urinary tract. Stones are more common among middle-aged and older adults. Stones vary in size from too small to be seen with the naked eye to 1 inch (2.5 centimeters) or more in diameter. A large, so-called staghorn (because of its many projections that resemble a deer's antlers), stone may fill almost the entire renal pelvis (the central collecting chamber of the kidney) and the tubes that drain into it (calyces).
A urinary tract infection may result when bacteria become trapped in urine that pools above a blockage. When stones block the urinary tract for a long time, urine backs up in the tubes inside the kidney, causing excessive pressure that can cause the kidney to swell (hydronephrosis) and eventually damage it.
Causes of Urinary Tract Stones
Stones may form because the urine becomes too saturated with salts that can form stones or because the urine lacks the normal inhibitors of stone formation. Citrate is such an inhibitor because it normally binds with calcium that is often involved in forming stones.
Stones are more common among people with certain disorders (for example, hyperparathyroidism, dehydration, and renal tubular acidosis) and among people whose diet is very high in animal-source protein or vitamin C or who do not consume enough water or calcium. People who have a family history of stone formation are more likely to have calcium stones and to have them more often. People who have undergone surgery for weight loss (bariatric surgery) may also be at increased risk of stone formation.
Rarely, drugs (including indinavir) and substances in the diet (such as melamine) cause stones.
Treatment of Urinary Tract Stones
Small stones that are not causing symptoms, blockage of the urinary tract, or an infection usually do not need to be treated and often pass on their own. Larger stones (over three sixteenths of an inch [5 mm]) and those that are closer to the kidney are less likely to pass on their own. Some drugs (tamsulosin or calcium channel blockers) may increase the likelihood of spontaneous stone passage.
Pain relief
The pain of renal colic may be relieved with NSAIDs. If the pain is severe, opioids are sometimes needed.
Stone-passing strategies
Drinking plenty of fluids or receiving large amounts of fluids intravenously has been recommended to help stones pass, but it is not clear that this approach is helpful. Alpha-adrenergic blockers (such as tamsulosin) may help the stone pass. Once a stone has passed, no other immediate treatment is needed.
Stone-bypass procedures
Sometimes when a blockage is severe, doctors insert a temporary tube (stent) in the ureter to bypass the obstructing stone. Doctors insert a telescopic viewing instrument (cystoscope, a kind of endoscope) into the bladder and pass the stent through the cystoscope and into the opening of the ureter. The stent is pushed up past the obstructing stone. The stent is left in place until the stone can be removed (for example, by surgery).
Alternatively, doctors may drain the blockage by inserting a drainage tube through the back into the kidney (nephrostomy tube).
Stone removal
Often, shock wave lithotripsy can be used to break up a stone in the renal pelvis or uppermost part of the ureter that is ½ inch (1 centimeter) or less in diameter. In this procedure, shock waves directed at the body by a sound wave generator break up the stone. The pieces of stone are then passed in the urine. Sometimes, a stone is removed with grasping forceps using an endoscope (viewing tube) through a small incision in the skin, or the stone can be shattered into fragments using a probe from a lithotripsy machine and then the pieces are passed in the urine. Sometimes, a laser is used to break up the stone. When a laser is used, the procedure is called holmium laser lithotripsy.
Address：No. 810，Building D， Riverside Financial and Commercial Center， No. 112 Chazishan East Rd, Yuelu District, Changsha City, P.R. of China
Tel：0086-731-84253199 
Email：rawmaterial@yazetrading.com