BACKGROUND: Patients with hyperthyroidism have increased plasma levels of von Willebrand factor (vWF). Changes in tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1), another two endothelium-derived proteins and modulators of blood fibrinolytic activity, have not been reported in hyperthyroidism. METHODS: The release of t-PA by vascular endothelial cells after venous occlusion, basal blood concentrations of t-PA, PAI-1 and vWF were studied in 33 patients with hyperthyroidism, with most of them followed up 30 days after iodine radiotherapy. RESULTS: Compared with control subjects, both the basal t-PA levels in plasma and the increase in t-PA levels with venous occlusion were significantly decreased in patients (P < 0.001), whereas plasma PAI-1 and vWF levels were increased greatly (P < 0.001). At follow-up, patients with normal plasma free thyroxine (T4) and total tri-iodothyronine (T3) showed similar plasma levels of t-PA, PAI-1, vWF and release of t-PA from endothelial cells as the control subjects (P > 0.05). In those with persistent elevated T4 or T3 levels, however, the basal plasma t-PA level and the released t-PA from endothelial cells during venous occlusion were significantly lower than in the control subjects (P < 0.001 and P < 0.005), and blood concentrations of PAI-1 and vWF did not return to the normal range (P < 0.001 and P < 0.001). In all patients, serum thyroid hormone concentrations were inversely correlated with basal plasma t-PA (T4: r = -0.549, P < 0. 001; T3: r = -0.463, P < 0.001) and released t-PA by endothelial cells (T4: r = -0.505, P < 0.001; T3: r = -0.450, P < 0.001) but strongly correlated with plasma PAI-1 (T4: r = 0.613, P < 0.001; T3: r = 0.577, P < 0.001) and vWF (T4: r = 0.457, P < 0.001; T3: r = 0. 564, P < 0.001). CONCLUSION: Hyperthyroid patients may experience vascular endothelial dysfunction and reduced fibrinolytic activity in blood.
BACKGROUND:Patients with hyperthyroidism have increased plasma levels of von Willebrand factor (vWF). Changes in tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1), another two endothelium-derived proteins and modulators of blood fibrinolytic activity, have not been reported in hyperthyroidism. METHODS: The release of t-PA by vascular endothelial cells after venous occlusion, basal blood concentrations of t-PA, PAI-1 and vWF were studied in 33 patients with hyperthyroidism, with most of them followed up 30 days after iodine radiotherapy. RESULTS: Compared with control subjects, both the basal t-PA levels in plasma and the increase in t-PA levels with venous occlusion were significantly decreased in patients (P < 0.001), whereas plasma PAI-1 and vWF levels were increased greatly (P < 0.001). At follow-up, patients with normal plasma free thyroxine (T4) and total tri-iodothyronine (T3) showed similar plasma levels of t-PA, PAI-1, vWF and release of t-PA from endothelial cells as the control subjects (P > 0.05). In those with persistent elevated T4 or T3 levels, however, the basal plasma t-PA level and the released t-PA from endothelial cells during venous occlusion were significantly lower than in the control subjects (P < 0.001 and P < 0.005), and blood concentrations of PAI-1 and vWF did not return to the normal range (P < 0.001 and P < 0.001). In all patients, serum thyroid hormone concentrations were inversely correlated with basal plasma t-PA (T4: r = -0.549, P < 0. 001; T3: r = -0.463, P < 0.001) and released t-PA by endothelial cells (T4: r = -0.505, P < 0.001; T3: r = -0.450, P < 0.001) but strongly correlated with plasma PAI-1 (T4: r = 0.613, P < 0.001; T3: r = 0.577, P < 0.001) and vWF (T4: r = 0.457, P < 0.001; T3: r = 0. 564, P < 0.001). CONCLUSION: Hyperthyroid patients may experience vascular endothelial dysfunction and reduced fibrinolytic activity in blood.
Authors: Anna Popławska-Kita; Katarzyna Siewko; Beata Telejko; Anna Modzelewska; Janusz Myśliwiec; Robert Milewski; Maria Górska; Małgorzata Szelachowska Journal: Int J Endocrinol Date: 2013-12-03 Impact factor: 3.257