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Kidney Stones Health Center

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Kidney Stone Analysis

How It Is Done

The kidney stone you take to the lab will be cleaned of any blood or tissue and then looked at to find what chemicals it is made of.

How It Feels

The most common way a kidney stone is collected for this test is by passing it in urine. Passing a stone may be painless or it may be very painful. The pain can begin suddenly and may come and go. A sand-sized stone may pass with little pain. A larger stone may cause a lot of pain in the lower back, groin, or genitals as it moves down the ureters or the urethra.

A small stone may pass without medical treatment. A large stone may need surgery or another type of procedure to get it out.

Risks

There is no chance for problems with kidney stone analysis. But a kidney stone can:

  • Have bacteria that can cause a urinary tract infection (UTI).
  • Damage the kidney, especially if the stone is a staghorn (struvite) stone.
  • Block the urinary tract. This can happen while the stone is passing through the tract.

Results

Kidney stone analysis is a test done on a kidney stone to see what chemicals are in it.

Knowing the type of kidney stone helps guide the best treatment choice. Your doctor will talk with you about treatment and prevention measures.

  • About 80% of kidney stones are made of calcium oxalate, calcium phosphate, or a combination of both.1
  • About 10% to 15% of kidney stones are made of magnesium ammonium phosphate (struvite).1
  • About 5% to 10% of kidney stones are made of uric acid.1
  • Less than 1% of kidney stones are made of a chemical called cystine.1

What Affects the Test

Putting tape on a kidney stone to keep it safe on the way to the lab may cause a problem with the test results.

What To Think About

  • About 80% of kidney stones in the ureters can be seen on an X-ray.
  • A computed tomography (CT) scan of the ureters and kidneys (also called a CT urogram) is the most common way to find kidney stones. To learn more, see the topic CT Scan of the Body.
  • Ultrasound may also be used to find kidney stones. To learn more, see the topic Abdominal Ultrasound.
  • Another test that can be done to find a kidney stone is intravenous pyelogram (IVP). During IVP, a dye is put into a vein in your arm. As the dye moves to the kidneys, X-rays are taken to watch the movement of the dye and see where a stone may be. To learn more, see the topic Intravenous Pyelogram (IVP).
  • Most kidney stones have calcium in them. A low-calcium diet does not often prevent stones from forming. To learn more about lowering your chance for a kidney stone, see the topic Kidney Stones.
  • Knowing the type of kidney stone helps guide the best treatment choice.

WebMD Medical Reference from Healthwise

Last Updated: September 24, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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