The uric acid test is used to learn whether the body might be breaking down cells too quickly or not getting rid of uric acid quickly enough. The test also is used to monitor levels of uric acid when a patient has had chemotherapy or radiation treatments.

The uric acid test is ordered when a doctor suspects high levels of uric acid. Some patients with high levels of uric acid have a disease called gout, which is an inherited disorder that affects purine breakdown. Patients with gout suffer from joint pain, most often in their toes but in other joints as well. The test also is ordered as a monitoring test when a patient has undergone chemotherapy or radiation, to learn whether uric acid levels are getting dangerously high. The test may also be ordered if a patient appears to have failing kidneys. Patients who have high uric acid levels are sometimes put on a drug regimen to help lower uric acid levels.

Higher than normal uric acid levels mean that the body is not handling the breakdown of purines well. The doctor will have to learn whether the cause is the over-production of uric acid, or if the body is unable to clear away the uric acid.

Increased concentrations of uric acid can cause crystals to form in the joints, which leads to the joint inflammation and pain characteristic of gout. Uric acid can also form crystals or kidney stones that can damage the kidneys.

Low levels of uric acid in the blood are seen much less commonly than high levels and are seldom considered cause for concern. Although low values can be associated with some kinds of liver or kidney diseases, exposure to toxic compounds, and rarely as the result of an inherited metabolic defect, these conditions are typically identified by other tests and symptoms and not by an isolated low uric acid result.

Many drugs can increase or decrease the level of uric acid. In particular, diuretic drugs like thiazide drugs can cause uric acid levels to go up.

Aspirin (and other salicylates) have varying effects on uric acid. At low aspirin levels (as may occur in persons taking aspirin only occasionally), aspirin can increase blood uric acid. On the other hand, in high doses (as may be used to treat rheumatoid arthritis), aspirin actually lowers the concentration of uric acid.

For people who have uric acid kidney stones or gout, foods that are high in purine content should be avoided, including organ meats (like liver and kidneys), sardines and anchovies. Alcohol also should be avoided, because it slows down the removal of uric acid from the body. Fasting, a starvation diet, and strenuous exercise all raise uric acid levels.

Although the uric acid test cannot definitively diagnose gout, a test for monosodium urate in synovial fluid (joint fluid) can.