Lupus anticoagulants (LA)
Detection tests are variably affected by NOAC, and test results are problematic to interpret. Because the reagents and methods employed are neither widely available nor standardized, they are not recommended for LA testing in patients on NOAC.
When the laboratory diagnosis of LA is needed, temporarily switching the patient from NOAC to low molecular weight heparin may be an alternative.
Protein C and Protein S activity
Protein C and Protein S activity may be overestimated. NOACs will increase the plasma clotting time and mimic increased protein C or protein S inhibitory activity. The effect may be reagent-dependent. No effect was reported when protein C inhibitory activity was measured as chromogenic activity.
