Identifying hypocoagulable states with a modified global assay of overall haemostasis potential in plasma

Abstract

To test the sensitivity of the global assay of overall haemostasis potential (OHP) in detecting hypocoagulation, the OHP was assayed in plasma containing exogenous thrombin (0.04 IU/ml), tissue-plasminogen activator (330 ng/ml), Ca and a platelet reagent. Commercial plasmas with factor II, V, VIII, IX, X, XI, XII or VII deficiency were mixed with normal plasma in different proportions to imitate different severities. Samples from patients with haemophilia and factor XII deficiency were also examined. No clot was found in the absence of factor II/factor X, indicating that the tiny dose of thrombin worked solely as a trigger for the intrinsic pathway activation. Changed levels of the investigated coagulants, apart from factor XII, influenced the outcome. OHPs were decreased in patients with haemophilia but were unchanged or even increased in those with factor XII deficiency. This modified OHP method may therefore be useful for estimating the bleeding tendency in haemophilic patients and to find suitable doses and intervals for prophylactic treatment. It may also be of use in investigations of the effect of antifibrinolytic drugs as well as for identifying a thrombotic tendency in patients with factor XII deficiency. For detection of other coagulation factor deficiencies, our investigations with the commercial plasmas suggest that the OHP assay is also valuable, especially when the intrinsic pathway of the coagulation cascade is impaired.

Clinical Application of Fibrinolytic Assays

“…The OHP has demonstrated sensitivity to changes in both coagulation and fibrinolytic factors. In vitro experiments using factor deficient plasma have demonstrated significant correlations between OHP parameters and concentrations of factors II, V, VII, VIII, IX and X and XI [142]. These results were replicated in our laboratory, and we also have shown using in-vitro experiments that the OFP parameter is sensitive to varying concentrations of plasminogen, α2-plasmin inhibitor, PAI-1, TAFI and the fibrinolytic inhibitor tranexamic acid [unpublished data and 143].…”

The Overall Hemostasis Potential: A Laboratory Tool for the Investigation of Global Hemostasis

“…Thus highly significant correlations between OHP levels and rising concentrations of different coagulation factors (II, V, VII, VIII, IX, X, and XI) were observed in an in vitro model. 13 Furthermore, investigation of plasma from patients with different severities of hemophilia A indicated that OHP levels correlated better with clinical features in these patients than those that could be concluded from the actual levels of FVIII or aPTT. This is in accordance with findings in clinical practice that patients having similar levels of deficiency of clotting factors show different degrees of severity in clinical presentation and bleeding tendencies.…”

“…Various modifications of the assay were made in later studies. 12,13 Briefly, after addition of thrombin at a lower dose (i.e., 0.04 IU/mL) and platelet reagent as a source of phospholipids, with and without tPA (at 330 ng/mL), to PPP, Abs values are recorded each minute for 40 minutes at a wavelength of 405 nm. Two fibrinaggregation curves are formed and the two AUCs are calculated: that is, the OHP (tPA added) and the overall coagulation potential (OCP; tPA not added) ( Figs.…”

Platelet Activity, Coagulation, and Fibrinolysis During Exercise in Healthy Males

“…The overall hemostasis potential assay we previously used 8 was modified. Briefly, 50 L of a fibrin formation-triggering cocktail containing rTF, PPL, and CaCl 2 , without or with rt-PA was added to 150 L aliquots of plasma to initiate analyses of the coagulation profile (Cp) and the fibrinolysis profile (Fp), respectively.…”

“…7 However, the balance between coagulation and fibrinolysis during exercise has not been well defined. This issue may be addressed by measurements of the overall hemostasis potential, 8,9 which measures the balance between thrombininduced fibrin gel formation and plasmin-induced fibrin digestion. Furthermore, as exercise enhances fibrinolysis, it is of considerable interest to investigate how exercise influences the fibrin gel network, being the final outcome of coagulation, using a permeability assay.…”