What is a uric acid test?

A uric acid test measures the amount of uric acid in the body. Uric acid is a chemical that’s produced when your body breaks down purines. Purines are compounds that enter the bloodstream during the natural breakdown of cells in the body. They’re also created during the digestion of certain foods, such as:

  • anchovies
  • sardines
  • mushrooms
  • mackerel
  • peas
  • liver

Once purines release uric acid, most of it’s dissolved in the blood and transported to the kidneys, where it’s removed from the body through urination. Some uric acid also leaves the body through defecation. When this process is disrupted, however, your body can produce too much or too little uric acid.

A uric acid test is often performed to help determine the underlying cause of abnormal uric acid levels. By measuring the amount of uric acid in your body, your doctor can evaluate how well your body is producing and removing uric acid. Your doctor can perform a uric acid blood test, or they can test your uric acid using a urine sample.

Your doctor will usually recommend a uric acid urine test when you’re showing symptoms of a medical condition that causes uric acid levels to rise.

An increased amount of uric acid in the urine often indicates gout, which is a common form of arthritis. This condition is characterized by severe pain and tenderness in the joints, especially those in the toes and ankles. Other symptoms of gout include:

  • swelling in a joint
  • reddened or discolored skin around a joint
  • a joint that’s hot to the touch

A high amount of uric acid in the urine can also be a sign of kidney stones. Kidney stones are solid masses made of crystals. The excess uric acid in the body causes the formation of these crystals in the urinary tract. The symptoms of kidney stones include:

Your doctor may order a uric acid urine test to determine how well you’re recovering from either kidney stones or gout. A uric acid urine test might also be used to monitor your condition if you’re undergoing chemotherapy or radiation treatment. These treatments can lead to an accumulation of uric acid in the body.

It’s important to tell your doctor about any prescription drugs, over-the-counter medicines, or supplements you’re taking before you have a uric acid urine test. Certain medications can affect the accuracy of this test, including aspirin (Bufferin), ibuprofen (Advil), and water pills. Your doctor may tell you to stop taking these medicines prior to the test. Your doctor may also ask you to refrain from drinking alcohol immediately before and during the test.

A uric acid urine test is a safe, painless procedure that requires only the collection of urine. The urine samples need to be collected over a 24-hour period. Your doctor will explain how to collect the urine properly.

The urine collection procedure is as follows:

  1. On day 1, urinate into the toilet after waking up. Flush this first sample away.
  2. After that, take note of the time and collect all urine for the remaining 24 hours. Store the urine samples in a refrigerator or other cool place.
  3. Return the containers to the appropriate person as soon as possible.

It’s important to wash your hands carefully before and after collecting each urine sample. Make sure to cap the containers tightly and to label the containers.

Once the samples have been collected, the urine is sent to a laboratory for analysis. The results will be delivered to your doctor within a few days. Your doctor will discuss your individual results with you and explain what they mean in further detail.

A normal uric acid level in the urine is 250 to 750 milligrams per 24 hours.

Higher-than-normal levels of uric acid in the urine often indicate gout or kidney stones. Other causes include:

  • a diet high in foods containing purines
  • obesity
  • liver disease
  • kidney disease
  • bone marrow disorders, such as leukemia
  • metastatic cancer, or cancer that has spread to other parts of the body

In some cases, the test may show lower-than-normal levels of uric acid in the urine. This may indicate:

Depending on the results, your doctor may need to perform additional tests to confirm a diagnosis.