Uric Acid, Urine

Uric Acid, Urine

Synonym/acronym: Urine urate.

Common use

To assist in confirming a diagnosis of gout, assess renal function, evaluate for genetic defects related to uric acid levels, and monitor the effectiveness of therapeutic interventions.

Specimen

Urine (5 mL) from a random or timed specimen collected in a clean plastic, unrefrigerated collection container. Sodium hydroxide preservative may be recommended to prevent precipitation of urates.

Normal findings

(Method: Spectrophotometry)
GenderConventional UnitsSI Units (Conventional Units × 0.0059)
Male250–800 mg/24 hr1.48–4.72 mmol/24 hr
Female250–750 mg/24 hr1.48–4.43 mmol/24 hr
Values reflect average purine diet.

Description

Uric acid is the end product of purine metabolism. Purines are important constituents of nucleic acids; purine turnover occurs continuously in the body, producing substantial amounts of uric acid even in the absence of purine intake from dietary sources such as organ meats (e.g., liver, thymus gland and/or pancreas [sweetbreads], kidney), legumes, and yeasts. Uric acid is filtered, absorbed, and secreted by the kidneys and is a common constituent of urine. The ratio of 24-hr urine uric acid to creatinine can be used as a test for detection of the Lesch-Nyhan syndrome, a disorder of uric acid metabolism associated with absence of the enzyme hypoxanthine-guanine phosphoribosyltransferase. The ratio in healthy patients is reported to range from 0.21 to 0.59. Patients with partial or complete enzyme deficiency can have ratios from 2 to 5.

This procedure is contraindicated for

    N/A

Indications

  • Compare urine and serum uric acid levels to provide an index of renal function
  • Detect enzyme deficiencies and metabolic disturbances that affect the body’s production of uric acid
  • Monitor the response to therapy with uricosuric drugs
  • Monitor urinary effects of disorders that cause hyperuricemia

Potential diagnosis

Increased in

  • Disorders associated with impaired renal tubular absorption, such as Fanconi’s syndrome and Wilson’s disease
  • Disorders of purine metabolism
  • Excessive dietary intake of purines
  • Gout
  • Neoplastic disorders, such as leukemia, lymphosarcoma, and multiple myeloma (related to increased cell turnover)
  • Pernicious anemia (related to increased cell turnover)
  • Polycythemia vera (related to increased cell turnover)
  • Renal calculus formation (related to increased urinary excretion)
  • Sickle cell anemia (related to increased cell turnover)

Decreased in

    Chronic alcohol ingestion (related to decreased excretion) Hypertension (related to decreased excretion) Severe renal damage (possibly resulting from chronic glomerulonephritis, collagen disorders, diabetic glomerulosclerosis, lactic acidosis, ketoacidosis, or alcohol abuse)

Critical findings

    N/A

Interfering factors

  • Drugs that may increase urine uric acid levels include acetohexamide, ampicillin, ascorbic acid, azapropazone, benzbromarone, chlorpromazine, chlorprothixene, corticotropin, coumarin, dicumarol, ethyl biscoumacetate, iodipamide, iodopyracet, iopanoic acid, ipodate, mannose, merbarone, mercaptopurine, mersalyl, methotrexate, niacinamide, nifedipine, phenindione, phenolsulfonphthalein, phenylbutazone, phloridzin, probenecid, salicylates (long-term, large doses), seclazone, sulfinpyrazone, and verapamil.
  • Drugs that may decrease urine uric acid levels include acetazolamide, allopurinol, angiotensin, benzbromarone, bumetanide, chlorothiazide, chlorthalidone, ethacrynic acid, ethambutol, ethoxzolamide, hydrochlorothiazide, levarterenol, niacin, pyrazinoic acid, and thiazide diuretics.
  • All urine voided for the timed collection period must be included in the collection or else falsely decreased values may be obtained. Compare output records with volume collected to verify that all voids were included in the collection.

Nursing Implications and Procedure

Potential nursing problems

PROBLEMSIGNS & SYMPTOMSINTERVENTIONS
Fluid volume (Related to decreased glomerular filtration or the presence of the diuretic stage of renal disease)Overload: edema, shortness of breath, increased weight, ascites, rales, rhonchi, and diluted laboratory values. Deficit: decreased urinary output, fatigue, sunken eyes, dark urine, decreased blood pressure, increased heart rate, and altered mental statusManage underlying cause of fluid alteration; record accurate intake and output; monitor urine characteristics and respiratory status; establish baseline assessment data; collaborate to adjust oral and IV fluids to provide optimal hydration status
Electrolytes (Related to compromised excretion)Increased BUN, increased creatinine; decreased sodium, increased urine specific gravity; increased potassium; decreased sodium; decreased calcium; increased magnesium; increased phosphorus; altered uric acidMonitor laboratory values; administer appropriate IV infusions and medications to correct altered electrolytes as ordered; collaborate with physician in consideration of dialysis as appropriate to maintain homeostasis; monitor uric acid levels
Skin (Related to altered fluid and nutritional status and associated inactivity)Decreased skin turgor; dry mouth; furrowed tongue; dry lips; jaundiceMaintain mucous membrane and skin integrity; provide oral care; reposition every 2 hr or more frequent as needed
Confusion (Related to an alteration in fluid and electrolytes, hepatic disease, renal disease)Disorganized thinking, restlessness, irritability, altered concentration and attention span, changeable mental function over the day, hallucinationsTreat the medical condition; correlate confusion with the need to reverse altered electrolytes; evaluate medications; prevent falls and injury through appropriate use of postural support, bed alarm, or restraints; consider pharmacological interventions; record accurate intake and output to assess fluid status

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching:   Inform the patient this test can assist in diagnosing gout and kidney disease.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s genitourinary system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Review the procedure with the patient. Provide a nonmetallic urinal, bedpan, or toilet-mounted collection device. Address concerns about pain and explain that there should be no discomfort during the procedure.
  • Usually a 24-hr time frame for urine collection is ordered. Inform the patient that all urine must be saved during that 24-hr period. Instruct the patient not to void directly into the laboratory collection container. Instruct the patient to avoid defecating in the collection device and to keep toilet tissue out of the collection device to prevent contamination of the specimen. Place a sign in the bathroom to remind the patient to save all urine.
  • Instruct the patient to void all urine into the collection device and then to pour the urine into the laboratory collection container. Alternatively, the specimen can be left in the collection device for a health-care staff member to add to the laboratory collection container.
  • Sensitivity to social and cultural issues,  as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen containers with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection.
  • Random Specimen (Collect in Early Morning)

  • Clean-Catch Specimen
  • Instruct the male patient to (1) thoroughly wash his hands, (2) cleanse the meatus, (3) void a small amount into the toilet, and (4) void directly into the specimen container.
  • Instruct the female patient to (1) thoroughly wash her hands; (2) cleanse the labia from front to back; (3) while keeping the labia separated, void a small amount into the toilet; and (4) without interrupting the urine stream, void directly into the specimen container.
  • Indwelling Catheter

  • Put on gloves. Empty drainage tube of urine. It may be necessary to clamp off the catheter for 15 to 30 min before specimen collection. Cleanse specimen port with antiseptic swab, and then aspirate 5 mL of urine with a 21- to 25-gauge needle and syringe. Transfer urine to a sterile container.
  • Timed Specimen

  • Obtain a clean 3-L urine specimen container, toilet-mounted collection device, and plastic bag (for transport of the specimen container). The specimen must be refrigerated or kept on ice throughout the entire collection period. If an indwelling urinary catheter is in place, the drainage bag must be kept on ice.
  • Begin the test between 6 and 8 a.m. if possible. Collect first voiding and discard. Record the time the specimen was discarded as the beginning of the timed collection period. The next morning, ask the patient to void at the same time the collection was started and add this last voiding to the container. Urinary output should be recorded throughout the collection time.
  • If an indwelling catheter is in place, replace the tubing and container system at the start of the collection time. Keep the container system on ice during the collection period, or empty the urine into a larger container periodically during the collection period; monitor to ensure continued drainage, and conclude the test the next morning at the same hour the collection was begun.
  • At the conclusion of the test, comparethe quantity of urine with the urinary output record for the collection; if the specimen contains less than what was recorded as output, some urine may have been discarded, invalidating the test.
  • Include on the collection container’s label the amount of urine, test start and stop times, and any medications that can affect test results.
  • General

  • Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Increased uric acid levels may be associated with the formation of kidney stones. Educate the patient, if appropriate, on the importance of drinking a sufficient amount of water when kidney stones are suspected.
  • Nutritional Considerations: Note that increased uric acid levels may be associated with gout. Nutritional therapy may be appropriate for some patients identified as having gout. Educate the patient that foods high in oxalic acid include caffeinated beverages, raw blackberries, gooseberries and plums, whole-wheat bread, beets, carrots, beans, rhubarb, spinach, dry cocoa, and Ovaltine. Foods high in purines include organ meats, which should be restricted. In other cases, the requesting HCP may not prescribe a low-purine or purine-restricted diet for treatment of gout because medications can control the condition easily and effectively.
  • Recognize anxiety related to test results.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
    • Discuss the implications of abnormal test results on the patient’s lifestyle.
    • Provide teaching and information regarding the clinical implications of the test results, as appropriate.
    • Provide written and verbal information on the anatomy and physiology of the disease process.
    • Discuss lifestyle alterations that may improve health.
  • Expected Patient Outcomes

    • Knowledge
    • States food selections that are appropriate to health maintenance
    • Identifies reportable disease signs and symptoms
    • Skills
    • Accurately recognizes and reports disease signs and symptoms
    • Demonstrates how to weigh self-daily and maintain an accurate record for reporting results
    • Attitude
    • Expresses willingness to make necessary lifestyle changes to improve health management
    • Complies with following the therapeutic plan of care

Related Monographs

  • Related tests include arthroscopy, biopsy bone marrow, calcium, calculus kidney stone panel, cholesterol, collagen cross-linked telopeptide, CBC, CBC RBC count, CBC RBC indices, CBC RBC morphology, creatinine, creatinine clearance, gastrin stimulation, G6PD, lactic acid, lead, oxalate, PTH, parathyroid scan, phosphorus, sickle cell screen, synovial fluid analysis, UA, and uric acid blood.
  • Refer to the Genitourinary System table at the end of the book for related tests by body system.