comparison of clot-based vs chromogenic factor Xa procoagulant phospholipid activity assays.

We compared 2 commercial plasma procoagulant phospholipid activity (PPA) assays, chromogenic, using bound annexin V to capture phosphatidylserine-containing microparticles, and clot-based. In both, anionic phospholipids accelerated activation of prothrombin by factor Xa. PPA levels were lower in the chromogenic vs the clot-based assay, with poor correlation between methods: normal samples, mean ± SD, 27 ± 17 vs 590 ± 414 nmol/L (n = 24; r(2) = 0.