Uric Acid (Blood)

Does this test have other names?

Serum uric acid

What is this test?

This test measures the amount of uric acid in your blood.

Uric acid is a normal body waste product. It forms when chemicals called purines break down. Purines are a natural substance found in the body. They are also found in many foods, such as liver, shellfish, and alcohol. They can also be formed in the body when DNA is broken down. 

When purines are broken down to uric acid in the blood, the body gets rid of it when you urinate or have a bowel movement. But if your body makes too much uric acid, or if your kidneys aren't working well, uric acid can build up in the blood. Uric acid levels can also increase when you eat too many high-purine foods or take medicines like diuretics, aspirin, and niacin. Then crystals of uric acid can form and collect in the joints. This causes painful inflammation. This condition is called gout. It can also lead to kidney stones.

Why do I need this test?

You may need this test if your healthcare provider wants to see if you have high levels of uric acid in your blood. Your healthcare provider may advise this test if you have symptoms of gout, although most people with hyperuricemia don't develop gout. Symptoms of gout include:

• Joint pain or soreness

• Swelling and pain in a joint, such as the big toe, ankle, or knee, or red skin around a joint

• Joints that are hot to the touch

• Swelling and pain that affects only 1 joint in the body

• Skin that looks shiny and is red or purple

You may also need this test if you have symptoms of kidney stones. Symptoms include:

• Severe pain along your lower back. This may repeatedly get worse and then get better. The pain may also travel to your genitals.

• Nausea

• Vomiting

• Urgent need to urinate

• Blood in your urine

What other tests might I have along with this test?

You may have other tests to check for gout. For example, you may have a sample of joint fluid drawn out with a needle.

You may also have a urinalysis if your healthcare provider thinks that you have a kidney stone. The urinalysis looks for blood, white blood cells, and crystals.

You may have tests of your blood and urine to find out what's causing the high levels of uric acid.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in milligrams per deciliter (mg/dL). You may have too much uric acid in your blood (hyperuricemia) if your results are:

• Higher than 6 mg/dL if you are female

• Higher than 7 mg/dL if you are male

Many health conditions can cause high levels of uric acid. These include:

• Cancer

• Kidney disease

• Hypothyroidism

• Hyperparathyroidism

• Sarcoidosis

Your uric acid levels may be high if you eat foods high in purines. These include organ meats, dried beans and peas, and fish, such as anchovies, herring, sardines, and mackerel. High levels can also be caused by a low-salt diet.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

Some medicines may affect your test results. These include:

• Aspirin and other medicines that contain salicylate

• Levodopa, a medicine used to treat Parkinson disease

• Some diuretic medicines, such as hydrochlorothiazide

• Vitamin B-3 (niacin)

Other things that may affect your test results include:

• Vigorous exercise

• Chemotherapy or radiation therapy to treat cancer

• Foods high in purines, including organ meats, mushrooms, some types of fish and seafood, and dried peas and beans 

How do I get ready for this test?

Ask your healthcare provider if you should stay away from any foods, beverages, or medicines before the test.  Be sure your provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.