Uric acid - blood

Definition

Uric acid is a chemical created when the body breaks down substances called purines. Purines are normally produced in the body and are also found in some foods and drinks. Foods with high content of purines include liver, anchovies, mackerel, dried beans and peas, and beer.

Most uric acid dissolves in blood and travels to the kidneys. From there, it passes out in urine. If your body produces too much uric acid or does not remove enough of it, you can get sick. A high level of uric acid in the blood is called hyperuricemia.

This test checks to see how much uric acid you have in your blood. Another test can be used to check the level of uric acid in your urine.

Alternative Names

Gout - uric acid in blood; Hyperuricemia - uric acid in blood

How the Test is Performed

A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

You should not eat or drink anything for 4 hours before the test unless told otherwise.

Many medicines can interfere with blood test results.

• Your health care provider will tell you if you need to stop taking any medicines before you have this test.
• DO NOT stop or change your medicines without talking to your provider first.

Why the Test is Performed

This test is done to see if you have a high level of uric acid in your blood. High levels of uric acid can sometimes cause gout or kidney disease.

You may have this test if you have had or are about to have certain types of chemotherapy. Rapid destruction of cancerous cells or weight loss, which may occur with such treatments, can increase the amount of uric acid in your blood.

Normal Results

Normal values range between 3.5 to 7.2 milligrams per deciliter (mg/dL).

Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

The example above shows the common measurement range for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Greater-than-normal levels of uric acid (hyperuricemia) may be due to:

• Acidosis
• Alcoholism
• Chemotherapy-related side effects
• Dehydration, often due to diuretic medicines
• Diabetes
• Excessive exercise
• Hypoparathyroidism
• Lead poisoning
• Leukemia
• Medullary cystic kidney disease
• Polycythemia vera
• Purine-rich diet
• Renal failure
• Toxemia of pregnancy

Lower-than-normal levels of uric acid may be due to:

• Fanconi syndrome
• Hereditary diseases of metabolism
• HIV infection
• Liver disease
• Low purine diet
• Medicines such as fenofibrate, losartan, and trimethoprim-sulfmethoxazole
• Syndrome of inappropriate antidiuretic hormone (SIADH) secretion

Other reasons this test may be performed include:

• Chronic kidney disease
• Gout
• Injury of the kidney and ureter
• Kidney stones (nephrolithiasis)

References

Burns CM, Wortmann RL. Clinical features and treatment of gout. In: Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. Kelley and Firestein's Textbook of Rheumatology. 10th ed. Philadelphia, PA: Elsevier; 2017:chap 95.

Edwards NL. Crystal deposition diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 273.

Sharfuddin AA, Weisbord SD, Palevsky PM, Molitoris BA. Acute kidney injury. In: Skorecki K, Chertow GM, Marsden PA, Taal MW, Yu ASL, eds. Brenner and Rector's The Kidney. 10th ed. Philadelphia, PA: Elsevier; 2016:chap 31.