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. Foods and beverages with a high purine content include:
- dried beans
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 doesn’t filter out enough of it. Hyperuricemia is the name of the disorder that occurs when you have too much uric acid in your body.
High levels of uric acid are associated with a condition called gout. Gout is a form of arthritis that causes swelling of the joints, especially in the feet and big toes. Another cause of hyperuricemia is increased cell death, due to cancer or cancer treatments. This can lead to an accumulation of uric acid in the body.
It’s also possible to have too little uric acid in your blood, which is a symptom of liver or kidney disease. It’s also a symptom of Fanconi syndrome, a disorder of the kidney tubules that prevents the absorption of substances such as glucose and uric acid. These substance are then passed in the urine instead.
Most commonly, the test is used to:
- diagnose and monitor people with gout
- monitor people who are undergoing chemotherapy or radiation treatment
- check kidney function after an injury
- find the cause of kidney stones
- diagnose kidney disorders
You may need a uric acid test if:
- you have joint pain or swelling that may be related to gout
- you’re currently undergoing chemotherapy
- you’re about to start chemotherapy
- you have frequent kidney stones
- you’ve been diagnosed with gout in the past
Another option for uric acid testing is to test your urine over a 24-hour period. Sometimes your doctor will recommend both to confirm a diagnosis.
The following may interfere with your uric acid test results:
- certain medications, such as aspirin and ibuprofen (Motrin)
- high levels of vitamin C
- dyes used in X-ray tests
Tell your doctor about any prescription or over-the-counter medications or supplements you’re 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 another healthcare provider will take blood from a vein, usually from your inner elbow or the back of your hand. First, they’ll sterilize the area with an antiseptic. They will then wrap an elastic band around your arm to allow blood to fill the veins.
Then, they’ll insert a needle into your vein. The blood will be collected in an attached vial. Once the blood has been collected, the plastic band will be untied and the needle will be 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.
Uric acid levels can vary based on gender. According to the Clinical Reference Laboratory (CRL), normal values for women are 2.5 to 7.5 milligrams/deciliter (mg/dL) and 4.0 to 8.5 mg/dL for men. However, the values may vary based on the lab doing the testing.
According to the American College of Rheumatology (ACR), your target level if you have gout is a blood uric acid level of less than 6 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 typically indicate that your body is making too much uric acid or that your kidneys aren’t removing enough uric acid from your body. Having cancer or undergoing cancer treatment can also raise your uric acid levels.
High uric acid levels in your blood can also indicate of a variety of conditions, including:
- gout, which involves recurring attacks of acute arthritis
- bone marrow disorders, such as leukemia
- a diet high in purines
- hypoparathyroidism, which is a decrease in your parathyroid function
- kidney disorders, such as acute kidney failure
- kidney stones
- multiple myeloma, which is cancer of the plasma cells in your bone marrow
- metastasized cancer, which is cancer that has spread from its original site
The blood uric acid test isn’t considered a definitive test for gout. The only test that can absolutely confirm the presence of gout is testing a person’s joint fluid for monosodium urate. However, your doctor can make an educated guess based on high blood levels and your gout symptoms. Also, it’s possible to have high uric acid levels without the symptoms of gout. This is known as asymptomatic hyperuricemia.
Low levels of uric acid in the blood may suggest:
- Wilson’s disease, which is an inherited disorder that causes copper to build up in your body tissues
- Fanconi syndrome, which is a kidney 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. Uric acid blood tests may cause:
- pain or discomfort at the puncture site
- fainting or lightheadedness
- an accumulation of blood under your skin, such as hematoma or bruising
- infection at the puncture site
If you experience significant bleeding that won’t stop after the blood test, seek emergency medical treatment. However, this is a rare occurrence, as are the other complications noted here.
Your uric acid blood test results can help determine what treatments are appropriate. In some cases, you may not need treatment.
If your doctor diagnoses you with gout, this could include taking medicines to reduce pain and swelling. Dietary changes to cut back on purines can also help. Changing your diet can also benefit you if you have chronic uric acid kidney stones. If you’re undergoing different chemotherapy treatments, you may need frequent blood test monitoring to make sure your uric acid levels don’t become too high.