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Lab test

AspirinWorks 11-Dehydrothromboxane B2 (11-dhTXB2) with Creatinine Test

This urine test measures 11-dehydrothromboxane B2 (11-dhTXB2), the main breakdown product of platelet-derived thromboxane B2, reported together with urine creatinine.

Quest patient service center

About this test

Aspirin works by blocking an enzyme in platelets called cyclooxygenase, which lowers thrombosis risk by impairing platelet function. Quest notes that some people do not show this expected response, described as 'aspirin resistant.

This measurement may be used in people with cardiovascular disease before starting aspirin therapy, or in people who do not respond to aspirin's platelet-inhibiting effects.

Test details

CollectionQuest patient service center

Quest resources

Additional details

What this test looks at

The result reports three values from the same urine sample: 11-dhTXB2 itself, the 11-dhTXB2-to-creatinine ratio, and urine creatinine. Quest lists the methodology as a combination of calculation, enzymatic, and immunoassay methods used together to produce these three reported values.

This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It measures 11-dehydrothromboxane B2, the main breakdown product of platelet-derived thromboxane B2, in a urine sample, reported together with urine creatinine.

How is the sample collected?

The test uses a 4 mL random preserved urine sample.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

What is 'aspirin resistance'?

It is the term Quest uses for when a person with cardiovascular disease does not show the platelet-inhibiting response usually expected from aspirin. This test's result relates to that concept.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.