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Renal Calculi (Kidney Stones)

A stone that develops from crystals that form in urine and build up on the inner surfaces of the kidney, in the renal pelvis, or in the ureters. Kidney stones include calcium oxalate stones, cystine stones, struvite stones, and uric acid stones.

PubMed Health Glossary
(Source: NIH - National Institute of Diabetes and Digestive and Kidney Diseases)

About Kidney Stones

Kidney stones are hard pebbles that form inside your kidneys. Your kidneys are bean-shaped organs that filter the waste chemicals out of your blood and produce urine. Urine travels through your urinary tract to leave your body. The urine goes out of your kidneys, through your ureters (the tubes that connect the kidneys to the bladder; pronounced YUR-et-ers), and into your bladder. The bladder stores urine until it leaves your body when you urinate.

Kidney stones form when tiny mineral crystals in your urine stick together. Kidney stones can range in size and shape. They can be as small as a grain of sand or as large as a golf ball, although stones that big are rare.

If a kidney stone is small enough, it can move or "pass" through your urinary tract and out of your body on its own. If the stone is too large, however, it could get stuck in your kidney or ureter.

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What works? Research summarized

Evidence reviews

Increased water intake may help reduce the risk of recurrence of kidney stones but more studies are needed

Kidney stones (also known as calculi) are masses of crystals and protein and are common causes of urinary tract obstruction in adults. For a long time, increased water intake has been the main preventive measure for the disease and its recurrence. In this review only one study was found that looked at the effect of increase water intake on recurrence and time to recurrence. Increased water intake decreased the chance of recurrence and increased the time to recurrence. Further studies are needed.

Can percussion, diuresis, and inversion therapy improve outcomes for people with lower pole kidney stones following shock wave lithotripsy?

Lower pole kidney stones are challenging to treat effectively. Many people with lower pole kidney stones undergo shock wave lithotripsy to break up stones so they can be passed from the body in the urine. In some cases, stone fragments can be retained, and these can be difficult to eliminate. Better techniques are needed to help people pass small lower pole kidney stones or fragments that remain following shock wave lithotripsy.

Extracorporeal shock wave lithotripsy (ESWL) versus percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) for kidney stones

Stones in the urinary tract are a common medical problem. Half of patients with previous urinary stones have a recurrence within 10 years. Kidney stones can cause pain, blood in the urine, infection, decreased kidney function, and kidney failure. The treatment is to remove the stones from kidney. Extracorporeal shock wave lithotripsy (ESWL) disintegrates stones using shock waves and is a minimally invasive technique. Other minimally invasive methods (percutaneous nephrolithotomy (PCNL)) and retrograde intrarenal surgery (RIRS)) are widely used for kidney stones management because ESWL had limited success rate. This review aimed to compare the effectiveness and complications between ESWL and stones removing using the nephroscopy through the skin at kidney level (PCNL) or ureteroscope through the bladder and ureter to the kidney (RIRS). Five small randomised studies (338 patients) were included. Four studies compared ESWL with PCNL and one study compared ESWL with RIRS. Patients with kidney stones who undergo PCNL have a higher success rate than ESWL whereas RIRS was not significantly different from ESWL. However, ESWL patients spent less time in hospital, duration of treatment was shorter and there were fewer complications.

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Summaries for consumers

Treating kidney stones

Small kidney stones often pass on their own and don't need treatment as long as they don't cause any severe pain or complications. Larger kidney stones usually need to be removed. Depending on how large the kidney stones are and where they're located, they can be destroyed, removed using endoscopy or operated on. Kidney stones with a diameter of less than 5 millimeters pass on their own 70% of the time, and stones that are between 5 and 10 millimeters are flushed out in about 50% of cases. The amount of time this takes varies greatly. Small kidney stones are usually passed with the urine after one or two weeks. If a stone is expected to be flushed out with your urine without any treatment, it's usual to simply wait. Anti-inflammatory painkillers like diclofenac can provide relief if the kidney stone causes pain as it travels through the ureter. Larger stones will usually have to be broken up or surgically removed. This needs to be done in the following instances: The kidney stone isn't passed within four weeks.There are complications.It causes severe renal colic.The stone is larger than 10 mm in diameter. Uric acid stones can sometimes be dissolved using medication.

Increased water intake may help reduce the risk of recurrence of kidney stones but more studies are needed

Kidney stones (also known as calculi) are masses of crystals and protein and are common causes of urinary tract obstruction in adults. For a long time, increased water intake has been the main preventive measure for the disease and its recurrence. In this review only one study was found that looked at the effect of increase water intake on recurrence and time to recurrence. Increased water intake decreased the chance of recurrence and increased the time to recurrence. Further studies are needed.

Kidney stones: Overview

Kidney stones are very common, especially in people between the ages of 20 and 40. These small, hard deposits form in the renal pelvis and can enter a ureter. Larger stones can be painful and often have to be surgically removed. There are several options for treatment and prevention.

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Terms to know

Bladder
The organ that stores urine.
Calcium
A mineral needed for healthy teeth, bones, and other body tissues. It is the most common mineral in the body. A deposit of calcium in body tissues, such as breast tissue, may be a sign of disease.
Extracorporeal Shock Wave Lithotripsy (ESWL)
A method of breaking up bile stones, gallstones, and pancreatic and renal stones that uses a specialized tool and shock waves.
Imaging Tests
A type of test that makes pictures of areas inside the body. Some examples of imaging tests are CT scans and MRIs. Also called imaging procedure.
Kidney
One of a pair of organs in the abdomen. The kidneys remove waste and extra water from the blood (as urine) and help keep chemicals (such as sodium, potassium, and calcium) balanced in the body. The kidneys also make hormones that help control blood pressure and stimulate bone marrow to make red blood cells.
Percutaneous Nephrolithotomy
A method for removing kidney stones via surgery through a small incision in the back.
Renal Pelvis
The area at the center of the kidney. Urine collects here and is funneled into the ureter, the tube that connects the kidney to the bladder.
Ureter
The tube that carries urine from the kidney to the bladder.
Ureteroscopy
Examination of the inside of the kidney and ureter, using a ureteroscope. A ureteroscope is a thin, tube-like instrument with a light and a lens for viewing.
Urinary Tract
The organs of the body that produce and discharge urine. These include the kidneys, ureters, bladder, and urethra.
Urine
Liquid waste product filtered from the blood by the kidneys, stored in the bladder, and expelled from the body by the act of urinating.

More about Renal Calculi

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Also called: Renal stones, Nephrolith, Renal calculus

Other terms to know: See all 11
Bladder, Calcium, Extracorporeal Shock Wave Lithotripsy (ESWL)

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