What is a kidney stone analysis?
Kidney stones are small, pebble-like pieces of material that form in one or both of your kidneys. Kidney stones form when you have high levels of certain minerals or salts in your urine (pee).
A kidney stone analysis is a test to find out what a kidney stone is made of. This information helps your health care provider develop a plan to help you reduce your risk of forming more stones in the future.
There are four main types of kidney stones:
- Calcium is the most common type of stone.
- Uric acid is another common type of stone.
- Cystine is an uncommon type of stone. It is caused by cystinuria, a kidney disease that you inherit from your parents.
- Struvite is the most uncommon type of stone. It usually forms after a urinary tract infection (UTI).
Kidney stones can be as small as a grain of sand or as large as a pea, and sometimes even larger. Very small stones may pass out of your body when you urinate (pee). Larger or odd-shaped stones can get stuck inside your urinary tract and block the flow of urine. This may cause severe pain or bleeding, and you may need treatment to get rid of the stones. But with treatment, kidney stones usually don't cause permanent damage.
Other names: urinary stone analysis, renal calculus analysis
What is it used for?
A kidney stone analysis is used to find out what your kidney stone is made of. This helps your provider understand why the stone formed and what will help prevent more stones from forming in the future. This is important because once you've had a stone, you're likely to get another one.
Why do I need a kidney stone analysis?
You may need a kidney stone analysis if you have symptoms that could be from a kidney stone. These include:
What happens during a kidney stone analysis?
To collect a kidney stone, you will need a kidney stone strainer to filter your urine and a clean container for your stone. A kidney stone strainer is a device made of fine mesh or gauze. Your provider may give you a strainer, or you may get one from a drug store.
To collect your stone, you will:
- Filter all your urine through the strainer.
- Check the strainer carefully after each time you urinate to look for a stone. It may look like a grain of sand or a tiny piece of gravel.
- If you find a stone, put it in a clean container with a lid.
- DO NOT add anything to the container. The stone must be kept dry.
- DO NOT put tape or tissue on the stone.
- Return the container to your provider or lab as instructed.
A stone may pass at any time of the day or night. So, it's important to filter all your urine every time you urinate until you find a stone.
Your provider may tell you to drink a lot of water to help pass the stone. If you have pain while the stone is passing, ask your provider about pain medicine.
If your kidney stone is too large to pass, you may need a minor surgical procedure to remove the stone for testing. If you've already passed a kidney stone and you kept it, ask your provider about testing it.
Will I need to do anything to prepare for the test?
You don't need any special preparations for a kidney stone analysis.
Are there any risks to the test?
There is no known risk to having a kidney stone analysis. But passing a kidney stone may cause:
- Pain depending on the size of the stone
- A urinary tract infection
- A blocked urinary tract if the stone gets stuck
What do the results mean?
Your results will show what your kidney stone is made of. With this information, your provider will be able to recommend steps and/or medicines to help prevent more stones from forming. Your treatment plan will depend on the type of stone you have, but most plans include drinking plenty of water and changing some of the foods you eat.
If you have questions about your results, talk with your provider.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about a kidney stone analysis?
Calcium stones are the most common type, but they are not caused by eating dairy products. In fact, dairy products can help prevent calcium stones. Your provider can explain what diet changes can help reduce your risk for stones. This is important because kidney stones increase your risk for developing chronic kidney disease.
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- The University of Chicago [Internet]. University of Chicago Kidney Stone Evaluation and Treatment Program; c2022. Kidney Stone Types; [cited 2022 May 26]; [about 11 screens]. Available from: https://kidneystones.uchicago.edu/kidney-stone-types
- University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2022. Health Encyclopedia: Kidney Stone (Urine); [cited 2022 May 26]; [about 4 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=kidney_stone_urine
- UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2022. Kidney Stone Analysis;[updated 2021 Sep 8; cited 2022 May 26]; [about 3 screens]. Available from: https://patient.uwhealth.org/healthwise/article/en-us/hw7826
- UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2022. Kidney Stones;[updated 2021 Oct 18; cited 2022 May26]; [about 6 screens]. Available from: https://patient.uwhealth.org/healthwise/article/en-us/hw204795