ARGININE-VASOPRESSIN AND ENDOTHELIUM-ASSOCIATED PROTEINS IN THYROID-DISEASE

Plasma concentrations of endothelium-derived proteins (fibronectin and von Willebrand factor), liver synthesized proteins (haptoglobin, transferrin, ceruloplasmin, alpha(1)-antitrypsin, antithrombin III and factor VIII-coagulant) and plasma arginine-vasopressin (AVP) were measured in 12 hyperthyroid, 9 hypothyroid and 15 age- and sex-matched normal controls. In hyperthyroid patients the plasma concentrations of AVP and endothelium-associated proteins (EAP) were significantly higher than in the control group (p < 0.05 and p < 0.01 respectively). Rendering hyperthyroid patients into the euthyroid state significantly lowered AVP (p < 0.01), fibronectin (p < 0.05) and von Willebrand factor (p < 0.01) compared with pretreatment levels. Hypothyroid patients were studied at diagnosis and after replacement therapy with levothyroxine. Compared with pretreatment values, significant increases were noted in plasma concentrations of von Willebrand factor, fibronectin and AVP (p < 0.01). With the exception of factor VIII-coagulant, the concentrations of hepatic synthesized proteins did not deviate from normal values in hyperthyroid and hypothyroid patients. Significant correlations were found beween serum-free thyroxine on the one hand and the plasma concentrations of fibronectin (p < 0.005), von Willebrand factor (p < 0.001) and AVP (p < 0.0001). Similarly, there was significant correlation between the plasma concentrations of AVP on the one hand and fibronectin (p < 0.002) and von Willebrand factor (p < 0.01). The results demonstrate elevated plasma levels of AVP in hyperthyroid patients and an increase during levothyroxine treatment of hypothyroid patients. The increase in EAP (fibronectin and von Willebrand factor) was dependent on thyroid hormone, and correlated with the increase in the plasma AVP concentrations. The mechanism(s) underlying the interrelation between AVP, EAP and thyroid hormones is (are) yet to be defined.