Home
HelpTest ID TXBU 11-Dehydro-Thromboxane B2, Urine
Useful For
Assessing if a patient will derive benefit from aspirin therapy
Determining an individual’s risk of coronary heart disease and stroke
Identifying the effectiveness of antiplatelet therapies
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| AACT | Creatinine, U | No | Yes |
Testing Algorithm
When 11-dehydro-thromboxane B2 testing is performed, urine creatinine will always be performed at no additional charge.
Method Name
TXBU: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
AACT: Enzymatic Colorimetric Assay
Reporting Name
11-Dehydro-Thromboxane B2, USpecimen Type
UrineContainer/Tube: Plastic, 10-mL urine tube (T068)
Specimen Volume: 10 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Additional Information: Patient should not have taken nonsteroidal anti-inflammatory drugs within 72 hours or aspirin within 2 weeks prior to collection of a specimen.
Forms: If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/cardiovascular-request-form.pdf).
Specimen Minimum Volume
5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 90 days | |
| Ambient | 7 days |
Clinical Information
Antiplatelet medications are frequently utilized in the prevention of stroke, myocardial infarction, and vascular thrombotic diseases due to the fundamental role of platelet aggregation in a variety of atherothrombotic processes. Modulation of the prostaglandin thromboxane A2 (TxA2) pathway is 1 of the pivotal routes of activation involved in stimulating platelet aggregation. Synthesis of TxA2 is mediated in platelets by the cyclooxygenase 1 (COX-1) enzyme, which must be functional for stimulating the production of TxA2 from arachidonic acid.
The importance of TxA2 is demonstrated by the reduction in risk of myocardial infarction (MI) or death in patients with acute coronary syndrome (ACS) following administration of aspirin, which irreversibly inhibits platelet COX-1 and inhibits the production of TxA2. TxA2 has an extremely short half-life, converting to 2 stable, inactive metabolites: 11-dehydro-thromboxane B2 (TxB2) and 2, 3-dinor-11-dehydrothromboxane B2. Excretion of TxB2 in the urine has been shown to reflect in vivo platelet activation. Elevated concentrations of TxB2 have been noted in up to 85% of patients with acute ischemic stroke and demonstrate further diagnostic and prognostic utility in patients with ACS.
Aspirin therapy has been reported to reduce cardiovascular events in men and women by up to 40%. However, use of aspirin is not without risk and is associated with higher frequencies of gastrointestinal bleeding and hemorrhagic stroke. Identification of patients most likely to benefit from antiplatelet therapy with aspirin or other pharmaceutical agents has great clinical utility.
Quantitation of urinary TxB2 offers an advantage over platelet-activation markers measured in plasma or blood because measurements are not subject to interference from in vitro platelet activation, which commonly occurs as a result of preanalytical variables such as local vein trauma or insufficient anticoagulation during phlebotomy. Measurement of urine TxB2 may be performed in patients to assess the effectiveness of specific inhibition in the TxA2 pathway, along with identification of a patient’s ability to benefit from antiplatelet therapy, and their associated risk for developing future cardiovascular events.
Reference Values
≥18 years: 0-2,211 pg/mg creatinine
Reference values have not been established for patients who are <18 years of age.
Reference intervals apply to patients not taking agents known to influence platelet function (aspirin or other nonsteroidal anti-inflammatory drugs, thienopyridines, etc). Healthy individuals taking aspirin typically have 11-dehydro-thromboxane B2 concentrations below 500 pg/mg creatinine using this method.
Cautions
A variety of tests are available to assess platelet function and interpretation of results from 1 platform to another is confounded by the lack of standardization, because the tests quantitate different aspects of platelet function and use different cutoffs for determining appropriate response to the various antithrombotic therapies. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit inflammation via the cyclooxygenase 1 pathway, will lower thromboxane B2 concentrations and prevent an accurate baseline assessment of platelet reactivity and response. Patients should not take NSAIDs within 72 hours or aspirin within 2 weeks prior to providing a urine specimen for analysis.Day(s) Performed
Wednesday; 8 a.m.
Report Available
2 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
84431