How is it used?
The uric acid test is used to find out whether the body might be breaking down cells too quickly or not removing uric acid quickly enough. The test also is used to monitor levels of uric acid when a patient has had chemotherapy or radiation treatments.
Measurement of uric acid in urine is used to help diagnose the cause of recurrent kidney stone formation.
When is it requested?
The uric acid test is requested when a doctor suspects high levels of uric acid in blood. Most patients with raised levels of uric acid have no symptoms. Some patients with high levels of uric acid have a disease called gout, which causes joint pain and arthritis, most often in their toes but in other joints as well. The test may also be requested if a patient appears to have failing kidneys.
The test is also used as a monitoring test when a patient has undergone chemotherapy or radiation, to learn whether uric acid levels are getting dangerously high. Monitoring can also be done when a patient is found to have gout or renal failure. Patients who have high uric acid levels are sometimes put on drugs to help lower uric acid levels.
What does the test result mean?
Higher than normal uric acid levels mean that the body is not handling the breakdown of purines well. The doctor will have to find out whether the cause is over-production of uric acid, increased intake of purine-rich food, or if the body is unable to remove the uric acid because the kidneys are not working properly.
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.
There has been some discussion among doctors about the exact limits of a ‘normal’ test result for uric acid. The range of normal results is wide. Uric acid levels can vary every day in the same patient or throughout the year. Sometimes doctors will request several uric acid tests over a period of time to get a better idea of a patient’s level of uric acid.
Is there anything else I should know?
Many drugs can increase or decrease the level of uric acid. In particular, thiazide diuretic 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.