Uric acid - urine

Nitrogen test

Urea nitrogen urine test is performed to check for the amount of urea in urine. Urine is collected over a 24 hour period and is sent to the laboratory for testing. This test is mainly used to assess the amount of dietary protein needed by severely ill patients.

Definition

Uric acid is a chemical created when the body breaks down substances called purines. Purines are found in some foods and drinks, such as liver, anchovies, mackerel, dried beans and peas, beer, and wine. Purines are also a part of normal body substances, such as DNA.

Most uric acid dissolves in blood and travels to the kidneys, where it passes out in urine. If your body produces too much uric acid or doesn't remove enough of it, you may get sick. High levels of uric acid in the body is called hyperuricemia.

This test checks to see how much uric acid you have in your urine.

See also: Uric acid - blood

How the test is performed

A 24-hour urine sample is needed. See: 24-hour urine collection.

How to prepare for the test

Your doctor may tell you to stop taking any drugs that may affect the test results. For example, high levels of vitamin C and dyes used during certain x-rays may cause incorrect results.

Drugs that can interfere with test results include:

  • Alcohol
  • Allopurinol
  • Anti-inflammatory drugs (such as ibuprofen)
  • Salicylates (including aspirin)
  • Thiazide diuretics
  • Probenecid

This list may not be all-inclusive.

How the test will feel

The test involves only normal urination, and there is no discomfort.

Why the test is performed

This test may be done to diagnose the cause of kidney stones. It may also be used to monitor people with gout, since many of these patients develop uric acid kidney stones.

Normal Values

Normal values range from 250 to 750 milligrams per 24 hours.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Higher than normal uric acid levels in the urine may be due to:

  • Cancers that have spread (metastasized)
  • Disorders that affect the bone marrow or certain white blood cells
  • High-purine diet
  • Gout
  • Rhabdomyolysis
  • Lesch-Nyhan syndrome
  • Fanconi syndrome

Lower than normal uric acid levels in the urine may be due to:

References

McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. St. Louis, Mo: WB Saunders; 2006.

Bazari H. Approach to the patient with renal disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 115.

See also:

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    Polycythemia vera

    Polycythemia vera is an abnormal increase in the number of blood cells (primarily red blood cells) produced by the bone marrow.

  • Test

    Uric acid - blood

    Blood test

    Uric acid is a chemical created when the body breaks down substances called purines. Purines are found in some foods and drinks, such as liver, anchovies, mackerel, dried beans and peas, beer, and wine. Most uric acid dissolves in blood and travels to the kidneys, where it passes out in urine. If ...

  • Disease

    Liver disease

    Liver fattening, CT scan

    The term “liver disease” applies to many diseases and disorders that cause the liver to function improperly or stop functioning. Abdominal pain, yellowing of the skin or eyes (), or abnormal results of suggest you have liver disease. See also:

  • Disease

    Chronic glomerulonephritis

    Kidney anatomy

    Chronic glomerulonephritis is the advanced stage of a group of kidney disorders, resulting in inflammation and slowly worsening destruction of internal kidney structures called glomeruli.

  • Poison

    Lead poisoning

    Lead is a very strong poison. When a person swallows a lead object or breathes in lead dust, some of the poison can stay in the body and cause serious health problems.

  • Disease

    Gout

    Uric acid crystals

    Gout is a kind of arthritis that occurs when builds up in the joints. Acute gout is a painful condition that typically affects one joint. Chronic gout is repeated episodes of pain and inflammation, which may involve more than one joint.

Review date:
August 10, 2009
Reviewed by:
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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