Serum uric acid
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.
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.
Urgent need to urinate
Blood in your urine
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.
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:
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.
The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.
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.
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:
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 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.