How are kidney stones diagnosed?

To prevent more kidney stones, it's necessary to know what kind of stones you make. Most people make calcium stones, but there are different kinds of calcium stones. In fact, your body can produce about 16 different types of kidney stones. The first step is analyzing the stone. For your stone to be analyzed, you'll need to capture it when you urinate (unless your doctor took it out during a procedure). Your doctor will give you a strainer to urinate in, or you can urinate into a cup and filter your urine. Your doctor will send the stone to a lab to determine the chemicals in the stones.
The diagnosis of a kidney stone starts with a medical history, physical examination and imaging tests. Your doctors will want to know the exact size and shape of the kidney stones. This can be done with a high-resolution computed tomography (CT) scan from the kidneys down to the bladder, or an x-ray called a KUB x-ray (kidney-ureter-bladder x-ray), which will show the size of the stone and its position.

The KUB x-ray is often obtained by surgeons to determine if the stone is suitable for shock wave treatment. The KUB test may be used to monitor your stone before and after treatment, but the CT scan is usually preferred for diagnosis. In some people, doctors will also order an intravenous pyelogram (lVP), a special type of x- ray of the urinary system that is taken after injecting a dye.

Your doctor will want to find the cause of the stone. The stone will be analyzed after it comes out of your body, and your doctor will test your blood for calcium, phosphorus and uric acid. The doctor may also ask that you collect your urine for 24 hours to test for calcium and uric acid. Your doctor will know how to best treat your stone as they learn more from these tests.
The best way to know if you have a kidney stone is to get a urine test and some form of imaging. The urine test looks for blood in the urine. 
The simplest x-ray is a plain film x-ray of the abdomen (called a KUB) and can detect a kidney stone 70% of the time.

Another imaging technique is a kidney ultrasound which uses sound waves instead of radiation to identify kidney stones. However, the ultrasound cannot identify the ureters very well, so we often look to see if the collecting system is swollen if we suspect a ureteral stone.

The most sensitive technique is a computed tomography (CT) scan. A CT scan identifies everything and rarely misses a kidney stone. A low dose, non-contrast CT scan is all that is typically required.
Your doctor can diagnose your kidney stones (and rule out other possible causes of your symptoms) with urine and blood tests. You may also have a sonogram or computerized tomography (CT) scan so that your doctor can obtain images of your stones. It is helpful if these tests or your medical information can determine what kind of kidney stones you have and what treatment will work best; your doctor will probably want to examine the stone when it is out to set a plan to help prevent recurrence.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.