What Is a Uric Acid Test?

A uric acid blood test is a medical test used to check the amount of a normal waste product in your blood. It is also known as a serum urate (SU) test or as a uric acid level. It can be an important test in the diagnosis and management of gout and kidney stones.

Purpose of Test

To understand why you might need to a uric acid blood test, it’s helpful to learn about uric acid. Uric acid is a waste product made when your body breaks down purines, a component of your DNA and RNA. You also take in purines through your diet through various foods. The waste product of purines, uric acid, must be eliminated through your kidneys and your gastrointestinal tract.

Medical Problems From High Uric Acid

Having some uric acid in your blood is completely normal, but higher levels can cause medical issues. This is called hyperuricemia, and it can have a number of different underlying causes. Some of these include kidney disease, certain blood cancers, genetic errors of metabolism, hypothyroidism, psoriasis, rhabdomyolysis, hemolytic anemia, certain medications, and a diet rich in purines. It can be a problem if either a lot of cells are being broken down (creating a lot of purines) or if you are having trouble with removing the purines. But an underlying cause can’t always be identified.

Hyperuricemia can cause uric acid crystals to form inside your joints, leading to gout. High uric acid may make it more likely that you will get kidney stones (the type formed from uric acid). Hyperuricemia may also increase the risk of the development of chronic kidney disease, or worsen it if it is already present.

In most cases, you won’t get a test for uric acid blood test unless you have some sort of symptom or problem that needs a diagnosis. For example, you might need this test if you have a painful, red swollen joint, and your healthcare provider is seeing if you might have gout. Or you might need the test if you have kidney stones causing back pain, blood in your urine, and nausea. In that case, the uric acid blood test can help determine the most likely cause of the stone.

Uric Acid Monitoring During Cancer Treatment

People undergoing chemotherapy or radiation treatments for cancer also sometimes need a uric acid test. Cancer itself doesn’t cause high levels of uric acid, but these treatments can cause the death of many cells in your body. This can increase the blood levels of uric acid. This is most likely to be a problem for people with cancers affecting blood cells, but it can happen with any cancer type.

Having a uric acid test scheduled as a part of your cancer treatment helps your clinician keep an eye on your uric acid, which in turn helps prevent problems from hyperuricemia as a component of something called tumor lysis syndrome. The rapid breakdown of cells leads to very high levels of uric acid which damage the kidney and lead to problems with various electrolytes (salts in blood and body fluids). In this particular situation, the very high levels of uric acid can signal a life-threatening problem.

Risks and Contraindications

This test is performed via a simple blood draw, and there are no major risks involved. You might experience some slight pain or bleeding where your blood is drawn. Sometimes people feel a little light-headed.

Let your clinician know if you have any conditions that increase your risk of bleeding, like certain genetic conditions. Also make sure they are aware of any medications that you take that might increase bleeding, like warfarin.

Before the Test

Often, no test preparation is needed before getting a uric acid test. If you are having it done at the same time as certain other tests, you might need to fast before having your blood drawn. Ask your clinician if there are any preparations you need to make.

You might want to wear a loose-fitting shirt so it’s easy for the phlebotomist to assess a vein on your upper arm. The test might be performed at a hospital or in an outpatient setting.

During the Test

To perform the test, a healthcare professional needs to take a blood sample. Someone will clean the area. Next, a tourniquet will be applied above the vein to be used, usually in the upper arm. You may be asked to squeeze your fist while your phlebotomist finds a good vein to use. The needle will be inserted into a vein in your arm. This usually only hurts for a moment or two, and in total the whole process only takes a few minutes.

After the Test

The sample is promptly sent to a medical laboratory for analysis. Most of the time, you will be able to return to your normal activities right away. If you are dizzy after the blood draw, you may need to sit for a while or have something to eat or drink before going about the rest of your day. You might have some soreness or bruising where your blood was taken. Results of the test should come back fairly quickly, within a day or so.

Interpreting Results

Your results should tell you if your uric acid levels are too high or if they are in the normal range. Blood uric acid levels are usually given in milligrams per deciliter (mg/dL).

It’s important that this test result be considered with the results of the rest of your clinical situation. Not everyone with elevated uric acid develops gout, kidney stones, or kidney disease. Many people may have hyperuricemia without noticing any problems at all. You may be more likely to have problems from hyperuricemia if your level is very high and not just a bit above normal.

Your uric acid level is also sometimes important as a potential indicator for other diseases. For example, people with hyperuricemia may be more likely to have cardiovascular disease, high blood pressure, kidney disease, and diabetes. So, this test gives some information about your other medical risks.

Follow-Up

If you have elevated uric acid levels, your clinician may need other tests to assess what is going on and see what might be causing your elevated uric acid. For example, depending on your symptoms and your other medical problems, you might need some of the following:

• Urine test for uric acid
• Complete blood count (CBC)
• Complete metabolic panel
• Lipid profile
• Joint X-rays (to assess joint swelling)
• Joint aspiration (to look for uric acid crystals in the joint)
• Renal ultrasound (if kidney stones from uric acid are suspected) 

The results of these tests, in combination with the rest of your clinical picture, will help determine what treatment you might need.

Treatment, Treatment Goals, and Monitoring for Hyperuricemia

Depending on your overall medical profile, you may or may not need treatment and follow-up monitoring after your uric acid test. If you do have treatment for high uric acid levels, you may need follow-up tests to see if your levels respond. If needed, your provider can tweak your dose or change to another medication.

However, many people with hyperuricemia do not need treatment. If you aren’t having any symptoms related to hyperuricemia, you and your clinician may choose to simply monitor it. An exception to this might be someone who has hyperuricemia due to cancer treatment. In that case, you might need treatment to lower your uric acid levels, even if you aren’t experiencing symptoms.

Gout and Hyperuricemia

If you have hyperuricemia and gout, you may need to take to a type of medication known as urate-lowering therapy. These medications, such as allopurinol, help decrease the amount of uric acid in your blood. It’s thought that this reduces the formation of uric acid crystals in your joints. This, in turn, reduces the chances of having gout attacks in the future.

For people with gout and certain risk factors, the American Academy of Rheumatology recommends treating your uric acid to a level of less than 6 mg/dL. For example, you might need to target this level if you have two or more attacks of gout per year, or if you have chronic kidney disease. But you might need to target a lower number if your condition is more severe.

If you have gout, it’s important to ask your clinician about your current uric acid (serum urate) as well as your uric acid goal. In recent years, guidelines have encouraged clinicians to more tightly monitor the uric acid levels of their patients. But many people don’t receive optimal treatment to get their uric acid level low enough, and many people don’t know what their target number is for their uric acid blood test.

One challenge is that you may need to gradually increase your dose over time. It will also require some repeated blood tests to make sure you are taking the right dose for you. But if you work closely with your healthcare provider to get your dose just right, you may be able to decrease the likelihood of future attacks.

Kidney Stones and Hyperuricemia

Not everyone with kidney stones has problems with high uric acid. But people with certain types of chronic kidney stones from uric acid may also need to monitor their levels. This might require urine tests for uric acid and other substances as well as blood tests. In some cases, they may additionally need to take urate-lowering therapies or other treatments to reduce the risk of future stones.

A Word From Verywell

Interpreting medical test results can be confusing, so don’t hesitate to bring up all your questions. As always, remember to work with your healthcare provider to put your results in the context of your total health. Your uric acid level is one test that can give important information about potential treatment strategies. Fortunately, we have good treatments available for the hyperuricemia sometimes detected by this test.