Background and Objectives: Primary hyperparathyroidism (PHPT) is associated with an increased cardiovascular mortality and morbidity rate. However, the exact role of PTH and/or calcium in the development of cardiovascular disease (CVD) is still controversial. The influence of PHPT on hemostasis is yet unknown. Therefore, the main purpose of this study was to investigate the markers of endogenous coagulation/fibrinolysis and to evaluate the relationships between these hemostatic parameters, serum lipid profile and serum calcium and PTH in patients with PHPT. 

Design and Methods: Twenty-three patients with PHPT and 20 age-matched healthy controls were included in the study. Fibrinogen, factors V, VII, VIII, IX and X activities, von Willebrand factor (vWF), antithrombin III (AT III), protein C, protein S, tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor-1 (PAI-1), as well as common lipoprotein variables, were measured. The relationships between biochemical parameters and these hemostatic parameters were examinated. 

Results: Compared with the control subjects, platelet count, FVII, FX activities, and D-Dimer levels were significantly increased in patients with PHPT (p<0.001, p<0.05, p<0.001, and p<0.05, respectively). Among the lipids, the levels of TC, TG and LDL-C were significantly increased in patients with PHPT (p<0.01, p<0.001, p<0.001, respectively) than those in controls. In patients with PHPT, we showed a positive correlation between urinary phosphorus excretion and factors VIII, IX, and X (r: 0.572, p<0.01; r: 0.543, p<0.01; r: 0.532, p<0.01, respectively). F IX activity was positively correlated with TC (r: 0.463, p<0.05) and LDL-C (r: 0.549, p<0.01) There was a positive correlation between serum ALP and PAI-1 levels (r: 0.451, p<0.05). ApoB was positively correlated with D-Dimer (r: 0.421, p<0.05). We did not find any significant correlation between iPTH and serum calcium and the hemostatic parameters that we measured. 

Interpretation and Conclusions: In conclusion, we found some important differences in the hemostatic parameters between the patients with PHPT and healthy controls. increased platelet count, F VII and FX activities and ID-Dimer levels in patients with PHPT represent a potential hypercoagulable state, which might augment the risk for atherosclerotic and atherothrombotic complications. This condition may contribute to the excess mortality rate due to CVD in patients with PHPT.