Uric Acid in Urine

Why It Is Done

This test is done to:

• See if kidney stones were caused by high uric acid levels.
• Find the cause of a high level of uric acid in the blood and help choose the proper treatment.

How To Prepare

No special preparation is needed. You don't need to limit liquids or foods before the test. Make sure you drink enough liquids during the 24-hour test so that you don't get dehydrated.

During the 24-hour period, don't drink alcohol. It lowers the amount of uric acid eliminated by the kidneys.

Many medicines can change the results of this test. Be sure to tell your doctor about all the over-the-counter and prescription medicines you take.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).

How It Is Done

A uric acid urine test is usually done at home. You must collect all the urine you produce in a 24-hour period.

• You start collecting your urine in the morning. When you first get up, empty your bladder. But do not save this urine. Write down the time that you urinated to mark the beginning of your 24-hour collection period.
• For the next 24 hours, collect all of your urine. Your doctor or lab will usually provide you with a large container that holds about 1 gal (4 L). The container has a small amount of preservative in it. Urinate into a small, clean container. Then pour the urine into the large container. Don't touch the inside of the container with your fingers.
• Keep the large container in the refrigerator when you aren't using it.
• Empty your bladder for the last time at or just before the end of the 24-hour period. Add this urine to the large container, and record the time.
• Do not get toilet paper, pubic hair, stool (feces), menstrual blood, or other foreign matter in the urine sample.

How It Feels

Taking a 24-hour urine sample does not cause pain.

What Affects the Test

Test results might not be accurate if you don't collect exactly 24 hours of urine.

There are many things that can cause your level of uric acid to be too high or too low.

High values

High uric acid levels may be caused by conditions such as:

• Kidney disease or kidney damage.
• Some types of cancer (including leukemia, lymphoma, and multiple myeloma) or cancer treatments.
• Hemolytic anemia, sickle cell anemia, or heart failure.
• Disorders such as alcohol dependence, preeclampsia, liver disease (cirrhosis), lipid disorders, obesity, psoriasis, hypothyroidism, and low blood levels of parathyroid hormone.
• Starvation, malnutrition, or lead poisoning.
• A rare inherited gene disorder called Lesch-Nyhan syndrome.

High levels may also be caused by:

• Certain medicines. These include some diuretics, vitamin C (ascorbic acid), lower doses of aspirin (75 to 80 mg aspirin daily), niacin, and some medicines used to treat leukemia, lymphoma, and tuberculosis.
• Contrast material used for some X-ray tests.
• Eating foods that are very high in purines. These include organ meats (liver, brains), red meats (beef, lamb), game meat (deer, elk), and some seafood (sardines, herring, scallops).
• Drinking a lot of alcohol, especially beer.

Low values

Low uric acid levels may be caused by:

• Gout.
• Kidney damage or disease.
• Folic acid deficiency or lead poisoning.
• Not eating enough protein.
• Some medicines, such as allopurinol, insulin, some diuretics, and high levels of aspirin.
• Drinking alcohol during the collection period.

What To Think About

• Having a high uric acid level doesn't always mean you have gout. You won't need treatment as long as you don't have symptoms.
• If you have kidney disease or have had a problem with kidney stones, your doctor may start treatment with a medicine, such as allopurinol, even if your uric acid levels are not too high.
• A person with tophi or uric acid kidney stones will be treated for high uric acid levels no matter what the results of the uric acid test are.
• Uric acid also may be measured in blood. To learn more, see the topic Uric Acid in Blood.