Kidney Stone Analysis
Reviewed
Also called: urinary stone analysis, renal calculus analysis
Kidney stone analysis is a laboratory test to find out what a kidney stone is made of. This helps your provider understand why the stone formed and what will help stop more stones from forming in the future. The four main types are calcium, uric acid, cystine, and struvite stones. The test itself has no known risk, but passing the stone may cause pain, infection, or blockage. Your results will guide your provider's recommendations for diet, lifestyle, and possibly medicines to prevent future stones.
Specimen: Kidney stone (passed in urine or surgically removed)
Why this test may be ordered
- To determine the chemical composition of a kidney stone you have passed or had removed.
- To help your provider understand why the stone formed and develop a plan to prevent future stones.
Preparation and collection
You do not need any special preparations for a kidney stone analysis.
You will filter all your urine through a kidney stone strainer (fine mesh or gauze) each time you urinate until you catch a stone. Place the stone in a clean, dry container with a lid. Do not add anything, tape, or tissue. Return the container to your provider or lab as instructed. If the stone is too large to pass, a minor surgical procedure may be needed to remove it for testing.
There is no known risk to having a kidney stone analysis. However, passing a kidney stone may cause pain depending on the size of the stone, a urinary tract infection, or a blocked urinary tract if the stone gets stuck.
Understanding results
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.
- Calcium stone: The stone is composed mainly of calcium (often calcium oxalate or calcium phosphate). This is the most common type of kidney stone. Limitation: Results are based on analysis of the stone; interpretation of the impact on your health and prevention plan should be discussed with your provider. Next step: Talk to your provider about dietary and lifestyle changes to reduce the risk of forming more calcium stones.
- Uric acid stone: The stone is composed mainly of uric acid. This is another common type of kidney stone. Limitation: Results are based on analysis of the stone; interpretation of the impact on your health and prevention plan should be discussed with your provider. Next step: Talk to your provider about medications or dietary changes to lower uric acid levels and prevent future stones.
- Cystine stone: The stone is composed mainly of cystine. This is an uncommon type of stone caused by cystinuria, a kidney disease that you inherit from your parents. Limitation: Results are based on analysis of the stone; interpretation of the impact on your health and prevention plan should be discussed with your provider. Next step: Talk to your provider about genetic counseling and treatment for cystinuria, a hereditary condition that causes cystine stones.
- Struvite stone: The stone is composed mainly of struvite. This is the most uncommon type of stone and usually forms after a urinary tract infection (UTI). Limitation: Results are based on analysis of the stone; interpretation of the impact on your health and prevention plan should be discussed with your provider. Next step: Talk to your provider about treating any underlying urinary tract infection and strategies to prevent infection-related stones.
- The test identifies the chemical composition of the stone but does not diagnose all underlying causes; follow-up with your provider is needed to determine why the stone formed and how to prevent future stones.
- Passing a kidney stone may cause pain, a urinary tract infection, or a blocked urinary tract if the stone gets stuck.
- The test itself has no known risk, but the process of collecting the stone involves passing the stone, which can be uncomfortable.
What to do next
With the results, your provider will recommend steps and/or medicines to help prevent more stones. Most plans include drinking plenty of water and changing some foods you eat. Calcium stones are the most common type, but they are not caused by dairy products—in fact, dairy can help prevent them. Your provider can explain specific diet changes.
- What is the chemical composition of my kidney stone?
- What type of stone do I have?
- What lifestyle or dietary changes can help prevent future stones?
- Do I need any additional testing to understand why the stone formed?