Uric Acid (Urine)
Does this test have other names?
Urinalysis, 24-hour urinalysis
What is this test?
This test looks for uric acid in your urine.
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.
Why do I need this test?
You may need this test if your healthcare provider suspects that you have gout. He or she may also use this test to monitor you while you have cancer treatment, or to check your urine after you have a kidney stone.
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:
What other tests might I have along with this test?
Your healthcare provider may also test the pH, or acidity, of your urine and check for a substance called creatinine. The only way your provider can diagnose the condition for sure is by measuring the levels of uric acid in your synovial fluid.
What do my test results mean?
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.
Adults normally lose about 500 to 600 milligrams (mg) of uric acid in their urine every 24 hours. If you're eating a normal diet, losing more than 800 mg a day is considered too much.
If you eat lots of animal protein or purines, you may have more uric acid in your urine. A number of health problems can also cause you to make more uric acid, including gout, leukemia, obesity, cancer treatment, ileostomy, glycogen storage diseases, and Lesch-Nyhan syndrome.
How is this test done?
This test requires a urine sample. Your healthcare provider may measure your uric acid levels using a 24-hour urine specimen. First you will empty your bladder completely in the morning without collecting it and note the time. Then you'll collect your urine every time you go to the bathroom over the next 24 hours.
Does this test post any risks?
This test poses no known risks.
What might affect my test results?
Certain medicines may affect your test results. They 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. These include organ meats, mushrooms, some types of fish and seafood, and dried peas and beans.
How do I get ready for this test?
Be sure your healthcare 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.