AspirinWorks® (11-Dehydro Thromboxane B2)

Create a Free Account to View Prices


Turnaround Time: 4 - 9 days
CPT Code:

84431, 82570

Test Type: 9 mL Urine (random), frozen
Stability Time:

Freeze on arrival (at LabCorp) Stability: Refrigerated for 24 hours


A means to assess aspirin effect.

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.

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.

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. PubMed 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. PubMed 9423790

Wu KK. Platelet activation mechanisms and markers in arterial thrombosis. J Intern Med. 1996; 239(1):17-34. PubMed 8551196

Collection Details:

Collection Instructions:

Urine collection cup and transfer tube with preservative. Recommend transfer tubes with preservative including BD C&S Vacutainer® tubes, or BD UAP Vacutainer® tubes (Becton, Dickinson and Co.), or Aspirin Works™ tubes containing Chlorstat tablets. Order through People Soft No. 23711.

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. Fill tube with urine sample, approximately 9 mL and no less than 6 mL minimum volume. Seal tightly with screw cap and invert the tube several times. Discard remainder of urine sample. Freeze transport tube.

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