The aim is to assess the effect of injectable anticoagulants (unfractionated heparin (UFH), low molecular weight heparins (LMWH), fondaparinux, danaparoid, argatroban) on lupus anticoagulant testing assays over broad anti-Xa activity ranges and to establish their potential for causing false-positive or false-negative results.

Citrated whole blood was collected from subjects with positive lupus anticoagulant (LA) testing and from subjects with negative LA testing. Injectable anticoagulants were prepared in demineralized water and added to plasma samples LA+ and LA- to obtain broad anti-Xa activity ranges. Anti-Xa measurement and LA testing were performed in neat and spiked plasma samples. LA testing was performed with 4 different analyzer-reagent combinations to represent almost all hemostasis manufacturers currently available. There will be no direct comparison between the LA+ and LA- groups, the objective is to evaluate the effect of increasing concentrations of injectable anticoagulants on these 2 distinct populations.

Inclusion Criteria:

• For all subjects:
• Adult male or female subject.
• In capacity to give informed consent to participate in the research.
• Affiliated to a Social Security system.

For the LA- group:

• Without a previous thrombosis and considered healthy on the basis of the interview and clinical examination.
• Without coagulation disease

For the LA+ group:

- Notion of the presence of lupus anticoagulant (according to ISTH criteria) and whose last test was positive.

Exclusion Criteria:

For all subjects:

• Medical history considered by the investigator to be incompatible with the trial
• Refused participation
• Recent administration of oral or injectable anticoagulants
• INR > 1.5
• Pregnant women, nursing mothers
• Guardianship, curatorship, deprived of liberty, safeguard of justice

Patients are recruited according to their LA status (LA- or LA+).