Diagnostic tests for kidney stones fall into three general categories: imaging, blood tests, and urinalysis. Here's what to expect.

X-rays are often used to diagnose kidney stones. Photo: Shutterstock

As I’ve written before, kidney stones share many symptoms with urinary tract infections. The way your doctor will be able to know the difference is through an array of diagnostic tests. These tests fall into three general categories: imaging, blood tests, and urinalysis. Here’s what you can expect if you go to an emergency department or a doctor complaining of symptoms that may indicate kidney stones.


Your doctor may order tests such as X-rays or a CT scan to see if evidence of stones shows up. Most kidney stones are easily visible on X-rays because of the fact that most kidney stones have a calcium component, much like our bones. A CT scan provides a more in-depth look inside your body and can be helpful in determining exactly where the stones are—the kidneys, the ureters, or the bladder.

Blood tests

As part of your initial examination, the urologist may take a blood sample and run a comprehensive metabolic panel. Blood tests can be used to diagnose and observe a variety of urologic conditions. Often, blood work results can help doctors determine if further lab tests, such as a parathyroid level, or treatments are necessary. Here are some common blood tests that health care providers use to help diagnose urologic conditions:

  • Blood urea nitrogen (BUN) test: Used to evaluate kidney function, diagnose kidney problems, and monitor dialysis results.
  • Creatinine test: A high level of creatinine in the blood may indicate kidney damage caused by kidney infection, kidney stones, or decreased blood flow to the kidneys.
  • Estimated glomerular filtration rate (eGFR): Will test how well the kidneys are working.
  • Prostate-specific antigen (PSA) tests: Used in men to screen for prostate cancer and to monitor prostate cancer treatment. PSA is a protein produced by the prostate gland. The PSA test also may be used to diagnose benign prostatic hyperplasia (BPH, enlarged prostate) and/or prostate infections in men.
  • Calcium test: Measures the level of calcium in the blood and can be used to screen for parathyroid disease.
  • Phosphate test: Measures for phosphate levels in the blood and used to diagnose kidney problems and monitor dialysis.
  • Uric acid test: Also known as serum uric acid measurement, this test determines how much uric acid is present in your blood and how well your body produces and removes this acid. Too much uric acid in your blood can lead to uric acid stones.


At your first visit, whether to the emergency department or to your urologist, both men and women will be asked to provide a urine sample for a urinalysis (“urine” + “analysis”). This is a test that examines the urine’s color, concentration, and content. It also tests the urine’s level of bilirubin, blood sugar, pH levels. Urinalysis can also reveal leukocytes (white blood cells) in the urine, as well as nitrates and other signs of infection.

The color of urine can vary from pale yellow to dark yellow, and even red, green, or blue. Urine can be affected by food coloring as well as certain foods such as beets, asparagus, blackberries, and yellow vegetables. The presence of bilirubin in the urine can make the urine dark in color, even olive green. Hemoglobin, which may indicate injury to the urinary tract, can make the urine pink or red.

The urine’s pH (acid-alkaline balance) can also tell you a lot about your health depending on how acidic or basic it is. A neutral pH is 7.0; acids are lower in pH and alkalines are higher. Urine that has a low pH is the perfect environment for the formation of kidney stones. It may also mean that you have one of a variety of conditions such as diarrhea, dehydration, or acidosis—a higher than normal amount of acid in your blood. If you eat a lot of meat, your urine will probably be more acidic than if you eat a more balanced diet including fruits and vegetables.

You can read more about how kidney stones are diagnosed and treated—and how you can keep yourself from getting kidney stones in the first place—in my book, Even Urologists Get Kidney Stones. Pick up your copy today.