Serum uric acid
This test measures the amount of uric acid in your blood.
Uric acid is a normal bodily waste product. It forms when chemicals called purines break down. Purines are a natural substance found in the body and 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 properly, uric acid can build up in the blood. Uric acid levels can also increase when you eat too many high-purine foods or take certain medicines like diuretics, aspirin, and niacin. Then crystals of uric acid can form and collect in the joints, causing painful inflammation. This condition is called gout.
You might need this test if your healthcare provider wants to see whether you have high levels of uric acid in your blood. Your provider may recommend this test if you have symptoms of gout, although most people with hyperuricemia don't develop gout. Symptoms of gout include:
Joint pain or tenderness
Swelling in a joint or reddened skin around a joint
Swelling and pain in the big toe, ankle, or knee
Joints that are hot to the touch
Swelling and pain that affects only one 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 ease up. The pain may also travel to your genitals.
Urgent need to urinate
Blood in your urine
Your healthcare provider may also order other tests to diagnose gout, include looking at a sample of joint fluid drawn out with a needle.
Your provider may also order a urinalysis if he or she suspects that you have a kidney stone. The urinalysis looks for blood, white blood cells, and crystals.
Your provider may also order tests of your blood and urine to find out what's causing the high levels uric acid.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.
Results are given in milligrams per deciliter (mg/dL). Here are results that may mean you have hyperuricemia:
For females: higher than 6 mg/dL
For males: higher than 7 mg/dL
Many health conditions can cause high levels of uric acid. These include cancer, kidney disease, hypothyroidism, hyperparathyroidism, and sarcoidosis.
Your uric acid levels may be high if you eat foods high in purines, such as organ meats, dried beans and peas, and certain fish – anchovies, herring, sardines, and mackerel. High levels can also be caused by a low-salt diet.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Certain medicines may affect your test results. These include:
Aspirin and other medicines that contain salicylate
Cyclosporine, a medicine sometimes used for autoimmune diseases
Levodopa, a medicine used to treat Parkinson disease
Certain diuretic medicines such as hydrochlorothiazide
Vitamin B-3 (niacin)
Other things that may affect your test results include:
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
Ask your healthcare provider if you should avoid any foods, beverages, or medications 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 illicit drugs you may use.