How is it used?
The uric acid blood test is used to detect high levels of this compound in the blood in order to help diagnose gout. The test is also used to monitor uric acid levels in people undergoing chemotherapy or radiation treatment for cancer. Rapid cell turnover from such treatment can result in an increased uric acid level.
The uric acid urine test is used to help diagnose the cause of recurrent kidney stones and to monitor people with gout for stone formation.
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When is it ordered?
The uric acid blood test is ordered when a health care provider suspects that someone has a high uric acid level. Some people with high levels of uric acid have a disease called gout, which is a common form of arthritis. People with gout suffer from pain, most often in their toes, but in other joints as well. The test is also ordered to monitor cancer patients undergoing chemotherapy or radiation therapy, to ensure that uric acid levels do not get dangerously high.
The urine uric acid test may be ordered when a person suffers from recurrent kidney stones or has gout and needs to be monitored for formation of these stones.
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What does the test result mean?
Blood
Higher than normal uric acid levels in the blood is called hyperuricemia and can be caused by the over-production of uric acid in the body or the inability of the kidneys to adequately remove enough uric acid from the body. Further investigation is needed to determine the cause of the overproduction or decreased excretion of uric acid.
There are several genetic inborn errors that effect purine . cancer, multiple myeloma, leukemias, and cancer chemotherapy can cause increased production of uric acid. Chronic renal disease, acidosis, , and alcoholism can cause decreased excretion.
Increased concentrations of uric acid can cause crystals to form in the , which can lead to the joint and pain characteristic of gout. Uric acid can also form crystals or kidney stones that can damage the kidneys.
The American College of Rheumatology published guidelines on the management of gout in 2012 that recommend that target serum urate (uric acid) levels should be below 6 mg/dL for people diagnosed with the condition.
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, Fanconi syndrome, exposure to toxic compounds, and rarely as the result of an inherited metabolic defect (Wilson disease), these conditions are typically identified by other tests and symptoms and not by an isolated low uric acid result.
Urine
High uric acid levels in the urine are seen with gout, multiple myeloma, metastatic cancer, leukemia, and a diet high in purines. Those at risk of kidney stones who have high uric acid levels in their urine may be given medication to prevent stone formation.
Low urine uric acid levels may be seen with kidney disease, chronic alcohol use, and lead poisoning.
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Is there anything else I should know?
Many drugs can increase or decrease the level of uric acid. In particular, 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 treatrheumatoid 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, rapid weight loss, stress, 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.
Some people may have a high level of uric acid in the blood without having associated or (hyperuricemia). However, general screening to detect this condition is not recommended, nor is treatment considered appropriate.