Uric Acid (Urine)
Does this test have other names?
Urinalysis, 24-hour urinalysis
What is this test?
This test measures the amount of uric acid in your urine.
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.
Why do I need this test?
You may need this test if your healthcare provider thinks 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 soreness
Swelling in a joint or red skin around a joint
Swelling and pain in a big toe, ankle, or knee
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:
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. You may also have a test to measure the levels of uric acid in your synovial fluid. This is the main way to diagnose gout.
What do my test results mean?
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
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:
How is this test done?
This test is done with a urine sample. Your healthcare provider may measure your uric acid levels using a 24-hour urine test. For this sample, you must collect all of your urine for 24 hours. Empty your bladder completely first in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours. You will collect it in a container that your healthcare provider or the lab gives you.
Does this test pose any risks?
This test poses no known risks.
What might affect my test results?
Some 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
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, such as 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 illegal drugs you may use.