Tissue factor pathway inhibitor (TFPI) in disseminated intravascular coagulation: low levels of the activated factor...

Tissue factor pathway inhibitor (TFPI) fractions and coagulation markers were determined in 26 patients with disseminated intravascular coagulation (DIC). Thrombin-antithrombin complex and fibrin monomer values were markedly elevated in all patients (P < 0.01). The median TFPI activity level (2.1 nmol/l) was lower than in normal controls (2.6 nmol/l; P < 0.01). The median free TFPI level was within the normal reference range, but seven patients had levels above and nine patients had levels below normal range. The median activated factor X (FXa)-TFPI complex level in patients (0.13 nmol/l) was lower than in controls (0.18 nmol/l; P < 0.01). Only one patient had a FXa-TFPI complex level above the normal range, while eight patients had levels below. In conclusion, TFPI activity, free TFPI antigen and FXa-TFPI complex levels vary considerably in DIC. Activation of coagulation may increase TFPI levels, as reported by other workers and supported by a positive correlation between tissue factor and free TFPI in the present material. A negative correlation between fibrin monomer and free TFPI (r = -0.46, P = 0.019) might indicate that hyperactive coagulation leads to consumption of TFPI. Subnormal FXa-TFPI levels in DIC, possibly caused by consumption, may imply a reduced capacity to inactivate the triggering factor VIIa-tissue factor complex.