Definition
The uric acid test is used to measure serum uric acid levels, the major end metabolite of purine. Disorders of purine metabolism, rapid destruction of nucleic acids, and conditions marked by impaired renal excretion characteristically raise serum uric acid levels.
The most specific laboratory method for detecting uric acid is spectrophotometric absorption after treatment of the specimen with the enzyme uricase.
Purpose
- To confirm the diagnosis of gout.
- To help detect renal dysfunction.
Procedure
Patient Preparation
- Explain to the patient that the uric acid test detects gout and kidney dysfunction.
- Tell the patient that the test requires a blood sample.
- Explain who will perform the venipuncture and when.
- Notify the laboratory and the physician of drugs the patient is taking that may affect test results; it may be necessary to restrict them.
- Instruct the patient to fast for 8 hours before the test.
- Explain to the patient that he may experience slight discomfort from the tourniquet and the needle puncture.
Implementation
- Perform a venipuncture and collect the sample in a 3-or-4 ml clot-activator tube.
Nursing Interventions
- Apply direct pressure to the venipuncture site until bleeding stops.
- Inform the patient that he may resume his usual diet and medications stopped before the test.
Interpretation
Normal Results
- In men, 3.4 to 7 mg/dl (SI, 202 to 416 µmol/L)
- In women, 2.3 to 6 mg/dl (SI, 143 to 357 µmol/L)
Abnormal Results
- Increased uric acid levels may indicate gout or impaired kidney function.
- Levels may also rise in hjeart failure, glycogen storage disease (type I, von Gierke’s disease), infection, hemolytic and sickle cell anemia, polycythemia, neoplasms, and psoriasis.
- Low uric acid levels may indicate defective tubular absorption (such as Fanconi’s syndrome) or acute hepatic atrophy.
Interfering Factors
- Failure to observe patient restrictions
- Loop diuretics, ethambutol, vincristine, pyrazinamide, thiazines, and low doses of aspirin (possible increase).
- Acetaminophen, ascorbic acid, and levodopa (possible false-high if using colorimetric method)
- Aspirin in high doses (possible decrease).
- Starvation, high purine diet, stress, and alcohol abuse (possible increase).
Complication
- Hematoma at the venipuncture site.
Precautions
- Handle the blood sample gently to prevent hemolysis.
- Send the urine specimen to the laboratory immediately after collection is completed.