Synonym

• Urate

Tubes

• Red, tiger top, or gel barrier tube preferred
• Green top tube also acceptable
• 5-7 mL of venous blood

Additional information

• 4-6 hrs of fasting preferred before the test
• Handle sample gently to prevent hemolysis

Info

• This test measures the concentration of uric acid in the blood
• Uric acid is one of the metabolic end products of the metabolism of DNA and RNA and is the final oxidation product of purine
• Uric acid is transported by plasma from the liver to the kidneys, where it is filtered, absorbed, and excreted (70%). The remainder of uric acid is excreted into the GI tract and degraded
• Some studies have indicated high uric acid levels are an independent risk factor for cardiovascular mortality

Clinical

• The clinical utility of serum uric acid levels include:
• To aid in the diagnosis of gout when there is a family history
• To evaluate renal failure
• To determine the cause of known or suspected renal calculi
• To evaluate and monitor (the extent of tissue destruction):
• Chemotherapy
• Excessive exercise
• Infection
• Malignancy
• Radiation therapy
• Starvation
• To evaluate possible liver damage
• To monitor pregnancy induced hypertension
• To monitor the therapeutic efficacy or side effects of drugs known to alter uric acid levels
• Some studies support hyperuricemia being an independent risk factor for cardiovascular mortality
• High normal or mildly increased serum uric acid levels appear associated with cerebral ischemia and also white matter hyperintense lesions on T2-weighted MRIs of the brain; indicating brain ischemic changes
• Hyperuricemia is primarily due to one of the following mechanisms:
• Excess purine consumption from dietary sources
• Overproduction of uric acid due to excessive cell breakdown and catabolism of nucleonic acid, as in gout
• Overproduction of uric acid due to excessive production and destruction of cells, as in leukemia
• Underexcretion of uric acid, as in renal disease, or thiazide diuretic therapy
• A high level of uric acid in the blood does not always mean that a person with a painful joint has gout. Only 10-15% of instances of hyperuricemia are caused by gout
• Hyperuricemia may be present with acute gouty arthritis, but is not a consistent finding (gouty arthritis is due to uric acid crystal formation in the synovial fluid which IS NOT related to serum uric acid level)
• Gout, pseudogout or septic arthritis can clinically present in similar fashion
• The prevalence rate of asymptomatic hyperuricemia in the general population is estimated at 2-13%

Additional information

• Normal day to day variation is about 10%
• Uric acid levels are higher in summer than in winter
• Normal diurnal variation is about 5% with higher values in the morning, and lower values in the afternoon
• Uric acid levels are higher in blind persons and autistic children
• In women, uric acid levels increase after age 50
• African Americans develop hyperuricemia more commonly than Whites
• Related laboratory tests include:
• Complete blood count
• Blood urea nitrogen (BUN)
• Creatinine
• Creatinine clearance
• Electrolytes
• Kidney stone analysis
• Synovial fluid analysis
• Urine uric acid

Nl Result

Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.

High Result

Conditions associated with hyperuricemia include:

• Decreased renal excretion of uric acid (90%)
• Acidosis
• Diabetic ketoacidosis
• Lactic acidosis
• Alcoholic ketoacidosis
• Starvation ketoacidosis
• Dehydration
• Endocrine disorders
• Addison's disease
• Hyperparathyroidism
• Hypothyroidism
• Pseudohypoparathyroidism
• Familial juvenile gouty nephropathy
• Berylliosis
• Bartter's syndrome
• Congestive heart failure
• Diabetes insipidus (nephrogenic)
• Down's syndrome
• Hyperlipidemia
• Hypertension
• Lead poisoning (Chronic)
• Metabolic syndrome X
• Preeclampsia and eclampsia
• Primary idiopathic hyperuricemia
• Renal diseases
• Acute uric acid nephropathy
• Chronic renal failure
• Familial juvenile hyperuricemic nephropathy (FJHN)
• Nephrolithiasis
• Prerenal azotemia
• Sarcoidosis
• Weight-loss (Dieting)
• Overproduction of uric acid (10%)
• Acute inflammatory disorders
• Consumption of purine-rich diet as in
• Organ meats (liver, thymus gland, pancreas, kidney liver, kidney, sweetbreads)
• Legumes
• Yeasts
• Caffeine
• Glycogenoses III, V, and VII
• Gout
• Inborn errors of metabolism
• Hypoxanthine-guanine phosphoribosyl-transferase (HPRTase) deficiency (Lesch-Nyhan syndrome)
• Phosphoribosyl pyrophosphate synthetase (PRPP synthase) overactivity
• Increased nucleic acid turnover
• Hemolytic Anemia
• Infectious Mononucleosis
• Leukemia
• Lymphoma
• Megaloblastic Anemia
• Multiple myeloma
• Polycythemia Vera
• Sickle cell anemia
• Liver disease
• Obesity
• Psoriasis
• Stress
• Tissue/Cell destruction due to chemotherapy and radiation therapy
• Combination of overproduction and decreased excretion
• Alcohol ingestion (especially beer)
• Fructose-1 aldolase deficiency
• Glycogen storage disease - G6PD deficiency
• Shock
• Strenuous exercise
• Drugs and substances
• Acetaminophen
• Acetazolamide
• Aldesleukin
• Amiloride
• Aminothiadiazole
• Ampicillin
• Anabolic steroids
• Androgens
• Antineoplastic agents
• Ascorbic acid
• Asparaginase
• Aspirin (low dose)
• Atenolol
• Azathioprine
• Basiliximab
• Benzthiazide
• Betaxolol
• Bisoprolol
• Bumetanide
• Busulfan
• Calcitriol
• Candesartan
• Capreomycin
• Carvedilol
• Chloral hydrate
• Chlorambucil
• Chlorothiazide
• Chlorthalidone
• Cimetidine
• Cisplatin
• Clopidogrel
• Clozapine
• Corn oil
• Cyclosporine
• Cyclothiazide
• Cytarabine
• Cytotoxics
• Dantrolene
• Dextran
• Diapamide
• Diazoxide
• Diclofenac
• Didanosine
• Diltiazem
• Disopyramide
• Donepezil
• Doxorubicin
• Epinephrine
• Epoetin alfa
• Ergothioneine
• Ethambutol
• Ethoxzolamide
• Etoposide
• Fludarabine
• Flumethiazide
• Furosemide
• Gentamicin
• Goserelin
• Granulocyte colony-stimulating factor
• Hydralazine
• Hydroflumethiazide
• Hydroxyurea
• Irbesartan
• Isoniazid
• Isosorbide dinitrate
• Isotretinoin
• Lansoprazole
• Leuprolide
• Levarterenol
• Levodopa
• Lisinopril
• Lomefloxacin
• Losartan
• Mechlorethamine
• Mefruside
• Mercaptopurine
• Mesalamine
• Methicillin
• Methotrexate
• Methoxyflurane
• Methyclothiazide
• Metolazone
• Misoprostol
• Mitomycin
• Morinamide
• Mycophenolate
• Nabumetone
• Naproxen
• Nelfinavir
• Niacin
• Nicotinic acid
• Nisoldipine
• Nizatidine
• Oxytetracycline
• Pancrelipase
• Paroxetine
• Pegaspargase
• Pentostatin
• Pergolide
• Phenelzine
• Phenothiazines
• Pindolol
• Piroxicam
• Polythiazide
• Prednisone
• Propranolol
• Propylthiouracil
• Pyrazinamide
• Quinethazone
• Ramipril
• Rifampin
• Riluzole
• Risperidone
• Ritonavir
• Sildenafil
• Sulfanilamide
• Tacrolimus
• Theophylline
• Thiazide diuretics
• Thioguanine
• Thiotepa
• Thiouric acid
• Timolol
• Triamterene
• Trichlormethiazide
• Trimetrexate
• Venlafaxine
• Vincristine
• Xylitol
• Zalcitabine

Low Result

Conditions associated with hypouricemia include:

• Acute Intermittent Porphyria
• Billiary Obstruction
• Chronic debilitating diseases

• Cystinosis
• Diet low in purine
• Lack of organ meats (liver, thymus gland, pancreas, kidney liver, kidney, sweetbreads)
• Lack of legumes
• Lack of yeasts
• Fanconi's syndrome
• Galactosemia
• Hemochromatosis
• Hypereosinophillic syndrome
• Hypophosphatemia
• Malignancies (rarely) such as Hodgkin's disease
• Pregnancy
• Renal tubular defects
• Smoking
• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
• Wilson's disease
• Xanthinuria
• Drugs and substances
• Acetohexamide
• Allopurinol
• Amlodipine
• Aspirin (high doses)
• Azathioprine
• Benzbromaron
• Benziodarone
• Cannabis
• Canola oil
• Chlorothiazide (given intravenously)
• Chlorpromazine
• Chlorprothixene
• Cidofovir
• Cinchophen
• Clofibrate
• Corticosteroids
• Corticotropin
• Cortisone
• Coumadin
• Diatrizoic acid
• Diethylstilbestrol
• Diflunisal
• Dipyrone
• Dobutamine
• Doxazosin
• Enalapril
• Estrogens
• Ethacrynic acid
• Etodolac
• Fenofibrate
• Flufenamic acid
• Glucocorticoids
• Glucose infusion
• Glyceryl guaiacolate
• Griseofulvin
• Guaifenesin
• Hydralazine
• Ibuprofen
• Iodipamide
• Iodopyracet
• Iopanoic acid
• Ipodate
• Lithium
• Mannitol
• Mefenamic acid
• Mersalyl
• Methyldopa
• Oxyphenbutazone
• Phenindione
• Phenolsulfonphthalein
• Prednisolone
• Probenecid
• Radiographic contrast agents
• Salicylates (high dose)
• Seclazone
• Sertraline
• Spironolactone
• Sulfamethoxazole
• Sulfinpyrazone
• THC
• Ticarcillin/clavulanate
• Verapamil
• Vinblastine
• Warfarin

References

• Bellomo G et al. Microalbuminuria and uric acid in healthy subjects. J Nephrol. 2006 Jul-Aug;19(4):458-64.
• Chow KM et al. Lead nephropathy: early leads from descriptive studies. Intern Med J. 2006 Oct;36(10):678-82.
• Culleton BF et al. Serum uric acid and risk for cardiovascular disease and death: The Framingham heart study. Annals of Internal Medicine 1999 131: 7-13.
• eMedicine from WebMD®. Hyperuricemia. [Homepage on the Internet] ©1996-2006. Last updated on June 22, 2005. Last accessed on November 29, 2006. Available at URL: http://www.emedicine.com/med/topic1112.htm
• Fang J et al. Serum uric acid and cardiovascular mortality. The NHANES 1 epidemiologic follow-up study, 1971-1992. JAMA 2000 283: 2404-2410.
• Gungor ES et al. Relationship between serum uric acid, creatinine, albumin and gestational diabetes mellitus. Clin Chem Lab Med. 2006;44(8):974-7.
• Laboratory Corporation of America®. Uric Acid, Serum. [Homepage on the internet]©2003. Last accessed on November 16, 2006. Available at URL: http://www.labcorp.com/datasets/labcorp/html/chapter/mono/pr009100.htm
• LabTestsOnline®. Uric Acid. [Homepage on the Internet] ©2001-2006. Last reviewed on August 5, 2006. Last accessed on November 16, 2006. Available at URL: http://www.labtestsonline.org/understanding/analytes/uric_acid/sample.html
• Lam C et al. Uric acid and preeclampsia. Semin Nephrol. 2005 Jan;25(1):56-60.
• Pascual E et al. Gout, diuretics and the kidney. Annals of the Rheumatic Diseases 2006;65:981-982; doi:10.1136/ard.2005.049023
• Perlstein TS et al. Uric Acid and the Development of Hypertension. The Normative Aging Study. Hypertension. 2006 Oct 23; [Epub ahead of print].
• Schretlen DJ, Inscore AB, Vannorsdall TD, et al. Serum uric acid and brain ischemia in normal elderly adults. Neurology. 2007 Oct 2;69(14):1418-23.
• Stiburkova B et al. Analysis of excretion fraction of uric Acid. Nucleosides Nucleotides Nucleic Acids. 2006;25(9):1301-4.
• Suliman ME et al. J-Shaped mortality relationship for uric acid in CKD. Am J Kidney Dis. 2006 Nov;48(5):761-71.
• UTMB Laboratory Survival Guide®. URIC ACID, serum. [Homepage on the Internet]© 2006. Last reviewed on February 2006. Last accessed on November 21, 2006. Available at URL: http://www.utmb.edu/lsg/LabSurvivalGuide/chem/URIC_ACIDserum.html