A uric acid blood test, also known as a serum uric acid measurement, determines how much uric acid is present in your blood. The test can help determine how well your body produces and removes uric acid.
Uric acid is a chemical produced when your body breaks down foods that contain organic compounds called purines. These foods include liver, anchovies, mackerel, dried beans, beer, and wine. Purines are also created through the natural process of cell breakdown in the body.
Most uric acid is dissolved in the blood, filtered through the kidneys, and expelled in the urine. Sometimes, the body produces too much uric acid or does not filter out enough of it. Hyperuricemia is the disorder that occurs when you have too much uric acid in your body. One cause of hyperuricemia is increased cell death, due to cancer or cancer treatments, can lead to an accumulation of uric acid in the body.
It is also possible to have too little uric acid in your blood, which is a symptom of liver or kidney disease, or Fanconi syndrome, a disorder of the kidney tubules that prevents the absorption of substances such as glucose and uric acid, which are then passed in the urine.
Most commonly, the test is used to:
- diagnose and monitor patients with gout
- monitor patients undergoing chemotherapy or radiation treatment
- check kidney function post-injury
- determine the cause of kidney stones
- diagnose kidney disorders
Alcohol, certain medications such as aspirin and ibuprofen or Motrin, high levels of vitamin C, and dyes used in X-ray tests may interfere with the uric acid test results. Tell your doctor about any prescription or over-the-counter medications or supplements you are taking.
You may need to fast (refrain from eating or drinking) for four hours before the test.
The process of obtaining a blood sample for testing is called venipuncture.
Your doctor or a health care provider will take blood from a vein, usually from your inner elbow or the back of your hand. First, your doctor will sterilize the area with an antiseptic. He or she will then wrap an elastic band around your arm to allow blood to fill the veins.
Then a needle will be inserted into a vein. The blood will be collect in an attached vial. Once the blood has been collected, the plastic band will be untied and the needle removed from the vein. Pressure will be applied to the site of the needle entry and a bandage will be applied if necessary.
For infants and young children, a small cut may be made on the arm and a test strip or slide used to collect a small sample of blood. The area is then cleaned and bandaged if necessary.
Once collected, the blood is sent to a laboratory for analysis.
Normal results are between 3.5 and 7.2 milligrams of uric acid per deciliter of blood (mg/dL). Low levels of uric acid are less common than high levels and are less of a health concern.
High levels of uric acid in your blood may suggest:
- gout (recurring attacks of acute arthritis)
- bone marrow disorders (such as leukemia)
- a diet high in purines
- hypoparathyroidism (decreased parathyroid gland function)
- kidney disorders (such as acute kidney failure)
- kidney stones
- multiple myeloma (cancer of the plasma cells in your bone marrow)
- metastasized cancer (cancer that has spread from its original site)
Low levels of uric acid in the blood may suggest:
- Wilson’s disease (an inherited disorder in which your tissues contain too much copper)
- Fanconi syndrome (a kidney tube disorder)
- liver or kidney disease
- a diet low in purines
Blood draws are routine and very safe. The risks associated with a uric acid blood test are the same as those associated with any blood draw, and may include:
- pain or discomfort at the puncture site
- fainting or lightheadedness
- blood accumulating under the skin (hematoma or bruising)
- infection at the puncture site