Various abnormalities of coagulation-fibrinolytic system have been reported in patients with thyroid dysfunction. Several studies indicate that coagulation and fibrinolytic system is disturbed in the patients with
hypothyroidism. Also, the influence of
hypothyroidism on hemostasis is controversial; both hypocoagulable and hypercoagulable states have been reported. The levels of plasma
thrombin-activatable fibrinolysis inhibitor (TAFI)
antigen and
tissue factor pathway inhibitor (
TFPI) have been investigated only once in patients with
hypothyroidism. Therefore, the main purpose of this study was to evaluate the profile of coagulation and fibrinolytic parameters including TAFI and
TFPI in patients with
hypothyroidism. Fifteen patients with untreated
hypothyroidism and 15 age-matched healthy controls were included in the study. Factors V(FV), VII (FVII), VIII (FVIII) activities,
von Willebrand factor (vWF),
protein C,
protein S,
thrombomodulin (TM),
TFPI, and TAFI were measured. The relationships between serum
thyroid hormones and these
hemostatic parameters were examined. Compared with the control subjects, FVII activity, and TM Ag and TAFI Ag levels were significantly increased in patients with
hypothyroidism, whereas FV, FVIII, vWF,
protein C and
protein S activities, and
TFPI Ag levels were significantly decreased. We did not find any significant correlation between serum
thyroid hormones and the
hemostatic parameters that we measured. In conclusion, we found some important differences in the
hemostatic parameters between the patients with
hypothyroidism and healthy controls. Increased FVII, TM, and TAFI and decreased FV, FVIII, vWF,
protein C,
protein S, and
TFPI in these patients represent a potential hypercoagulable and hypofibrinolytic state, possible endothelial dysfunction, which might augment the risk for atherosclerotic and atherothrombotic complications. Thus, disturbances of the
hemostatic system may contribute to the excess mortality due to
cardiovascular disease seen in patients with
hypothyroidism.