Uric Acid in Urine

Test Overview

The uric acid urine test measures the amount of uric acid in a sample of urine collected over 24 hours.

Uric acid is made from the natural breakdown of your body's cells. It's also made from the foods you eat. Your kidneys take uric acid out of your blood and put it into urine so that it can leave your body.

But if your body is making too much uric acid, the level in the urine can get too high. And if your kidneys aren't working the way they should, the level of uric acid in the urine can get too low.

High levels of uric acid can cause crystals to form in joints. This causes a painful problem called gout. If gout isn't treated, the crystals can build up and form hard lumpy deposits called tophi.

High uric acid levels can also cause kidney stones.

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 .

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 4 L (1 gal). 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.

Risks

A 24-hour urine sample doesn't cause any problems.

Results

The uric acid urine test measures the amount of uric acid in a sample of urine collected over 24 hours.

These numbers are just a guide. The range for "normal" varies from lab to lab. Your lab may have a different range. Your lab report should show what range your lab uses for "normal." Also, your doctor will evaluate your results based on your health and other factors. So a number that is outside the normal range here may still be normal for you.

Results are usually available in 1 to 2 days.

Uric acid in urine^{footnote 1}
Normal:	250–750 milligrams (mg) per 24-hour urine sample	1.48–4.43 millimoles (mmol) per 24-hour urine sample

Women typically have slightly lower uric acid levels than men.

Many conditions can change uric acid levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.

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.

References

Citations

Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted

Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.

Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.