Serum uric acid
This test measures the amount of uric acid in your blood.
Uric acid can build up in your blood if your body makes too much of it or your kidneys don't properly get rid of it when you urinate. Too much uric acid can cause gout. Gout is a painful form of arthritis that typically strikes joints in the big toe, but it can also affect other areas in the feet and elsewhere in the body.
Gout happens when uric acid gathers in the form of spiky crystals in your joints. Deposits of uric acid can also collect under the skin. In addition, uric acid can accumulate as stones in your kidneys.
A higher level of uric acid in your blood is a condition called hyperuricemia.
You might need this test if your doctor wants to see whether you have high levels of uric acid in your blood. Your doctor may recommend this test if you have symptoms of gout, although most people with hyperuricemia don't develop gout. Symptoms of gout include:
Joint pain that comes on rapidly and typically affects only one joint
Joint that's swollen and red
You may also need this test if you have symptoms of kidney stones. Symptoms include:
Severe pain along your lower back. This may repeatedly get worse and then ease up. The pain may also travel to your genitals.
Urgent need to urinate
Blood in your urine
Your doctor may also order other tests to diagnose gout, include looking at a sample of joint fluid drawn out with a needle.
Your doctor may also order a urinalysis if he or she suspects that you have a kidney stone. The urinalysis looks for blood, white blood cells, and crystals.
Your doctor may also order tests of your blood and urine to find out what's causing the high levels uric acid.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Results are given in milligrams per deciliter (mg/dL). Here are results that may mean you have hyperuricemia:
For females: higher than 6 mg/dL
For males: higher than 7 mg/dL
Many medical conditions can cause high levels of uric acid. These include cancer, kidney disease, hypothyroidism, hyperparathyroidism, and sarcoidosis.
Your uric acid levels may be high if you eat foods high in purines, such as organ meats, dried beans and peas, and certain fish – anchovies, herring, sardines, and mackerel. High levels can also be caused by a low-salt diet.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Certain medications can cause high levels of uric acid. These include:
Nicotinic acid (niacin)
Overusing laxatives can also cause high levels of uric acid, as can alcohol use and eating foods high in purines.
Ask your doctor if you should avoid any foods, beverages, or medications before the test. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.