Summary
The area under the thrombin generation curve (the endogenous thrombin potential; ETP)
has been proposed as a parameter for plasma-based hypercoagulability and to monitor
anticoagulant treatment. We present an ETP assay for the routine laboratory using
a centrifugal analyser. Throughput is 30 samples/h, within and between run imprecision
is 4-5.6%. Suitable substrates were developed for the ranges of 10-500% and 2-100%
of normal.
Independent of tissue factor concentration (if >4 pM), the normal value of the extrinsic
ETP is 384.8 ±51.7 nM.min. The intrinsic ETP, triggered by ellagic acid, is 414 ±
41 nM.min.
The ETP is decreased to 15 and 35% of normal by oral anticoagulation (INR 2.5-4.0)
and by heparin administration (APTT 1.5-2.5 X control).
The ETP is increased in untreated subjects with congenital antithrombin deficiency
and in women using oral contraceptives. In deep vein thrombosis (phlebographically
confirmed), it is increased by 29.4% (extrinsic) and 53% (intrinsic). In (angiographically
assessed) coronary artery disease the increase is by 10% and 17% respectively.