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Alternative namesRenal calculi; Kidney stones; Stones - kidney
DefinitionNephrolithiasis is a condition in which one or more stones are present in the pelvis or calyces of the kidney or in the ureter. (See also cystinuria .)
Causes, incidence, and risk factors
Kidney stone formation may result when the urine becomes overly concentrated with certain substances. These substances in the urine may complex to form small crystals and subsequently stones. Stones may not produce symptoms until they begin to move down the ureter, causing pain. The pain is severe and often starts in the flank region and moves down to the groin.
Kidney stones are common. About 5% of women and 10% of men will have at least one episode by age 70. Kidney stones affect about 2 out of every 1,000 people. Recurrence is common, and the risk of recurrence is greater if two or more episodes of kidney stones occur. Kidney stones are common in premature infants.
A personal or family history of stones is associated with increased risk of stone formation. Other risk factors include renal tubular acidosis and resultant nephrocalcinosis .
Some types of stones tend to run in families. Some types may be associated with other conditions such as bowel disease, ileal bypass for obesity , or renal tubule defects.
Other substances may crystallize, precipitate, and form stones.
Signs and testsPain may be severe enough to require narcotics. There may be tenderness when the abdomen or back is touched. If stones are severe, persistent, or recurrent, there may be signs of kidney failure .
Tests may reveal high levels of calcium in the blood or urine.
Treatment goals include relief of symptoms and prevention of further symptoms. (Kidney stones usually pass on their own.) Treatment varies depending on the type of stone and the extent of symptoms and/or complications. Hospitalization may be required if symptoms are severe.
When the stone passes, the urine should be strained and the stone saved for analysis to determine the type.
Drink enough fluids to produce a high urinary output. Water is encouraged, at least 6 to 8 glasses per day. Intravenous fluids may be required.
Analgesics (pain relievers) may be needed to control renal colic (pain associated with the passage of stones). Severe pain may require narcotic analgesics.
Depending on the type of stone, medications may be given to decrease stone formation and/or aid in the breakdown and excretion of the material causing the stone. These may include such medications as diuretics, phosphate solutions, allopurinol (for uric acid stones), antibiotics (for struvite stones), and medications that alkalinize the urine such as sodium bicarbonate or sodium citrate.
If the stone is not passed on its own, surgical removal may be required. Lithotripsy may be an alternative to surgery. Ultrasonic waves or shock waves are used to break up stones so that they may be expelled in the urine (extracorporeal shock-wave lithotripsy) or removed with an endoscope that is inserted into the kidney via a small flank incision (percutaneous nephrolithotomy).
Dietary modification may be needed to reduce the recurrence of some types of stones.
Expectations (prognosis)Kidney stones are painful but usually are excreted without causing permanent damage. They tend to recur, especially if the underlying cause is not found and treated.
Calling your health care providerCall your health care provider if symptoms indicate a kidney stone may be present.
Also call if symptoms of kidney stone recur, urination becomes painful, urine output decreases, or other new symptoms develop.
PreventionIf there is a history of stones, fluids should be encouraged to produce adequate amounts of dilute urine (usually 6 to 8 glasses of water per day). Depending on the type of stone, medications or other measures may be recommended to prevent recurrence.
Update Date: 10/17/2003Irfan A. Agha, M.D., Department of Medicine, Renal Division, St. Louis University, St. Louis, MO. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT