The blood uric acid test measures the amount of uric acid in a blood sample. Uric acid is produced from the natural breakdown of your body's cells and from the foods you eat.

Most of the uric acid is filtered out by the kidneys and passes out of the body in urine. A small amount passes out of the body in stool. But if too much uric acid is being produced or if the kidneys are not able to remove it from the blood normally, the level of uric acid in the blood increases.

High levels of uric acid in the blood can cause solid crystals to form within joints. This causes a painful condition called gout. If gout remains untreated, these uric acid crystals can build up in the joints and nearby tissues, forming hard lumpy deposits called tophi. High levels of uric acid may also cause kidney stones or kidney failure.

Why It Is Done

A uric acid blood test is done to:

• Help diagnose gout.
• Check to see if kidney stones may be caused by high uric acid levels in the body.
• Check to see if medicine that decreases uric acid levels is working.
• Check uric acid levels in people who are undergoing chemotherapy or radiation therapy. These treatments destroy cancer cells that then may leak uric acid into the blood.

How To Prepare

You do not need to do anything before you have this test.

Some medicines can change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may indicate. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?) .

How It Is Done

The health professional who takes a sample of your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.