AspirinWorks® (11-Dehydro Thromboxane B2)

CPT: 82570; 84431
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Test Details

Synonyms

  • 11-Dehydro Thromboxane B2
  • 11dhTxB2

Use

A means to assess aspirin effect.

Limitations

Urine samples that are too dilute will not yield accurate results. Approximately 30% of urinary 11dHTxB2 may be derived from extra platelet sources (eg, monocytes, macrophages), which can generate additional COX-a following aspirin inhibition, whereas platelets cannot. 11dHTxB2 may be elevated with inflammatory conditions resulting in the potential to underestimate the degree of aspirin effect on platelet COX-1.

Methodology

Enzyme-linked immunoassay. AspirinWorks® is a registered trademark of Corgenix Medical Corp, Broomfield, Colo.

Additional Information

Thromboxane B2 (TxB2) is the stable, inactive product of prostaglandin metabolism of thromboxane A2, which is renally cleared and, therefore, can be measured in the urine. Studies have shown that thromboxane B2 is a sensitive indicator of platelet activation. Since platelets participate in atherogenesis and contribute to acute, ischemic complications, elevated TxB2 levels may reflect ongoing cardiovascular, peripheral vascular, and cerebrovascular disease processes. TxB levels may also be of interest in conditions with increased platelet turnover, such as disseminated intravascular coagulation or immune thrombocytopenia. Studies of patients with diffuse atherosclerotic disease show that TxB2 may be a more sensitive measure of platelet activation than other platelet-specific proteins. Serum or plasma TxB2 assays are typically limited to a research setting because of the significant in vitro platelet instability.

Urinary TxB2 is of interest in monitoring the anticoagulant response to aspirin therapy since aspirin inhibits the formation of TxB2 in platelets. In patients responsive to aspirin therapy and taking an adequate dose, urinary 11-dehydro TxB2 levels should be reduced below a predetermined cutoff when compared to control values.

Specimen Requirements

Specimen

Urine (random), frozen

Volume

9 mL

Minimum Volume

6 mL

Container

Recommended collection tubes with preservatives include BD C&S Vacutainer® tubes or BD UAP Vacutainer® tubes (Becton Dickinson), or AsprinWorks™ tubes containing Chlorostat tablets. Order through PeopleSoft N° 23711, or (if needed), contact client services at 800-444-9111 to request AsprinWorks collection tubes with Chlorostat preservative tablets.

Collection

Samples should be collected in a urinary preservative and stored/shipped frozen at ≤-20°C. First morning voided urine is recommended but not required.

Label a urine collection cup with the patient's name, and provide the patient with instructions for collecting a random urine sample.

Transfer urine within 24 hours of collection into the appropriate transport tube containing preservative.

a) Fill tube with patient's urine sample, ie, approximately 9 mL and no less than 6 mL minimum volume.

b) Seal tightly with screw cap, and invert the tube several times.

Storage Instructions

Freeze on arrival (at LabCorp). Stable refrigerated for 24 hours.

Causes for Rejection

Improperly labeled specimens; insufficient quantity received; tube incompletely filled; urine specimen not frozen; sample too dilute

Clinical Information

References

Eikelboom JQ, Hirsh J, Weitz JI, et al. Aspirin-resistant thromboxane biosynthesis and the risk of myocardial infarction, stroke, or cardiovascular death in patients at high risk for cardiovascular events. Circulation. 2002; 105(14):1650-1655.11940542
Gresele P, Catalano M, Giammarresi C, et al. Platelet activation markers in patients with peripheral arterial disease−a prospective comparison of different platelet function tests. Thromb Haemost. 1997; 78(6):1434-1437.9423790
Wu KK. Platelet activation mechanisms and markers in arterial thrombosis. J Intern Med. 1996; 239(1):17-34.8551196

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
501620 11-dehydro TXB2/Creat Ratio 501621 11-dehydro TXB2/Creat Ratio pg/mg creat 49734-7
501620 11-dehydro TXB2/Creat Ratio 501622 Interpretation: N/A
501620 11-dehydro TXB2/Creat Ratio 501623 11-dehydro TXB2/Creat Ratio N/A

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