Test ID: TXBU
11-Dehydro-Thromboxane B2, Urine
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
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 Lists test(s) that are always performed, at an additional charge, with the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| AACT | Creatinine, U | No | Yes |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
When 11-dehydro-thromboxane B2 testing is performed, AACT/10064 Creatinine, Urine will always be performed at no additional charge.
Method Name A short description of the method used to perform the test
TXBU/83335: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
AACT/10064: Enzymatic Colorimetric Assay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
*Aspirin Effect
*Aspirin Resistance
*Aspirin Therapy
*Platelet Activation
*Platelet Aggregation
*Platelet Inhibition
*Note: These key words are related to how other manufacturers use the 11-dehydro-thromboxane B2 analyte. Utilization of this test for these purposes is not the intent of this assay.
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Plastic, 10-mL urine tube (Supply 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.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 90 days | |
| Ambient | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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 one 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 Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
> or =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.
Interpretation Provides information to assist in interpretation of the test results
The normal reference range was derived from an in-house normal donor study with individuals who were self-reported as not taking any aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or other lipid-lowering therapies. Elevated concentrations of urine TxB2 may indicate an increase in platelet activation and thrombosis resulting from atherosclerotic deposits or other vascular obstructions and may identify those individuals who may be at increased risk for an ischemic cardiovascular event. Elevations of TxB2 in patients already receiving antiplatelet therapies suggest a failure in the suppression of laboratory-assessed platelet function, a continued hypercoagulable state, and alternative antithrombotic or antiplatelet therapies may be considered.
The LC-MS/MS method is specific for TxB2 and is not subject to interference from the other metabolite of TxA2, the 2,3-dinor-TxB2 component.Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Supportive Data
An ELISA for quantitation of urine TxB2 is marketed under the name of AspirinWorks. The ELISA assay has a high correlation with the LC-MS/MS method for TxB2, however there is a bias between methods with LC-MS/MS producing concentrations 25% less than the ELISA method.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Patrono C, Garcia Rodriguez LA, Landolfi R, Baigent C: Low-dose aspirin for the prevention of atherothrombosis. N Engl J Med 2005;353:2373-2383
2. Gluckman TJ, McLean RC, Schulman SP, et al: Effects of aspirin responsiveness and platelet reactivity on early vein graft thrombosis after coronary artery bypass graft surgery. J Am Coll Cardiol 2011; 57: 1069-1077
3. Pignone M, Williams CD: Aspirin for primary prevention of cardiovascular disease in diabetes mellitus. Nature 2010;6:619-628
4. Eikelboom JW, Hankey GJ, Thom J, et al: Incomplete inhibition of thromboxane biosynthesis by acetylsalicylic acid: determinants and effect on cardiovascular risk. Circulation 2008;118:1705-1712
5. Armstrong PC, Truss NJ, Ali FY, et al: Aspirin and the in vitro linear relationship between thromboxane A2-mediated platelet aggregation and platelet production of thromboxane A2. J Thromb Haemost 2008;6:1933-1943
Method Description Describes how the test is performed and provides a method-specific reference
TxB2 is quantitated with an assay developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Urine specimens are vortexed thoroughly to reconstitute all of the native TxB2. Urine samples are adjusted to a pH of 2.0 +/-0.2 and incubated for 3 hours at ambient temperature to force all the urinary thromboxane into the closed ring form that is recognized by the LC-MS/MS method. After addition of d4 internal standard (d4-11-dTxB2) to the sample, it is positive pressure filtered and the 11-dTxB2 is separated from the urine matrix via turboflow online extraction. A Cyclone MAX anion-exchange column is used for the extraction, while a Waters Xbridge C8 is used for separation from other prostaglandins. From this column, the sample is transferred to an API 5000 MS/MS for instrumental analysis. A calibration curve is included with each batch of samples. This method does not have any cross-reactivity with the 2,3-dinor thromboxane B2 metabolite.(Lueke AJ, Saenger AK: Development and Validation of an LC-MS/MS Assay for Quantitation of Urinary Prostaglandins. Clin Chem 2011;57:A133)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Thursday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
84431
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 83335 | 11-Dehydro-Thromboxane B2, U | 50686-5 |
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