Uric acid - urine

Alternative names
Uricosuria

Definition
The uric acid urine test measures the amount of uric acid in urine.

How the test is performed
A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

     
  • On day 1, urinate into the toilet when you get up in the morning.  
  • Afterwards, collect all urine in a special container for the next 24 hours.  
  • On day 2, urinate into the container when you get up in the morning.  
  • Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

Infant:
Thoroughly wash the area around the urethra. Open a Urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Diaper as usual over the secured bag.

This procedure may take a couple of attempts - lively infants can displace the bag, causing the specimen to be absorbed by the diaper. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to prepare for the test
The health care provider may advise you to discontinue drugs that can affect the test (see “special considerations”).

If the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel
The test involves only normal urination, and there is no discomfort.

Why the test is performed

The most common reason for measuring uric acid levels is for evaluation, diagnosis, and treatment of kidney stones. Patients with gout may also be evaluated using this test, since a significant number of patients with gout develop uric acid kidney stones.

Uric acid is the end-product of purine catabolism. Purines (such as adenine and guanine) are components of nucleotides, which are the building blocks of the nucleic acids such as RNA and DNA.

Normal Values
Normal values range from 250 to 750 mg/24 hours. Normal value ranges may vary slightly among different laboratories.

Note: mg/24 hr = milligrams per 24 hours

What abnormal results mean

Abnormal results are indicated as follows:

Greater-than-normal urinary uric acid levels may indicate:

     
  • Metastatic cancers  
  • Myelogenous and lymphoproliferative disorders  
  • High purine diet  
  • Gout  
  • Rhabdomyolysis  
  • Lesch-Nyhan syndrome  
  • Fanconi syndrome

Lower-than-normal urinary uric acid levels may indicate:

     
  • Chronic alcohol ingestion  
  • Chronic glomerulonephritis  
  • Lead poisoning

Special considerations
Interfering factors for this test include:

     
  • High levels of vitamin C  
  • X-ray contrast agents

Drugs that can interfere with test results include: alcohol, anti-inflammatory drugs (such as NSAIDs), salicylates, thiazide diuretics, allopurinol, and probenecid.

Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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