Patient-independent variables affecting the assessment of aspirin responsiveness by serum thromboxane measurement

Giovanna Petrucci, Alessandro Rizzi, Viviana Cavalca, Aida Habib, Dario Pitocco, Fabrizio Veglia, Paola Ranalli, Francesco Zaccardi, Francesca Pagliaccia, Elena Tremoli, Carlo Patrono, Bianca Rocca

Research output: Contribution to journalArticlepeer-review


The serum TXB2 (sTXB2) assay reflects the pharmacodynamics of platelet inhibition by low-dose aspirin. However, different studies reported variable sTXB2 values. sTXB2 assay requires whole blood incubation at 37 °C as a condition for optimal thrombin generation, arachidonic acid release and its metabolism by platelet cyclooxygenase-1 to form TXA2. Access to 37 °C incubation may be variably delayed, and different methods to quantitate sTXB2 may contribute to variable results between different Centers. We investigated whether delaying 37 °C incubation and/or analytical issues affect sTXB2 concentrations, biasing the assessment of aspirin responsiveness. Sixty-eight samples from 54 volunteers, on-and off-aspirin, were incubated at 37 °C immediately after sampling (reference sample) or after 5, 10, 15, 20, 30 or 60 minutes at room temperature (RT); 8 samples remained at RT 60 minutes, without subsequent incubation; 314 sera were measured by enzyme immunoassay (EIA) and liquid chromatography-tandem massspectrometry (LC/MS-MS) methods. sTXB2 concentrations decreased exponentially as a function of the delay before 37 °C incubation, ranging from 94 ± 11 % at 5 minutes to 23 ± 22 % of the reference sample after 60 minutes at RT. There was high agreement between EIA and LC/MS-MS. Moreover, we simulated the influence of a 15‑or 30-minute delayed incubation on 300 sTXB2 measurements from previouslystudied, aspirin-treated patients. Delayed incubation reduced the percentage of aspirin ‘non-responders’ by 22 % to 52 %, depending on the response threshold. In conclusion, a variable delay in the 37 °C incubation of blood samples may affect the assessment of platelet cyclooxygenase-1 inhibition by aspirin and confound the characterization of the determinants of aspirin responsiveness.

Original languageEnglish
Pages (from-to)891-896
Number of pages6
JournalThrombosis and Haemostasis
Issue number5
Publication statusPublished - Nov 1 2016


  • Aspirin
  • Cyclooxygenase-1
  • Enzyme immunoassay
  • Liquid chromatographytandem mass spectrometry
  • Thromboxane B

ASJC Scopus subject areas

  • Hematology


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