Abstract: Abstract Objective Study on the change of the level of the endothelial progenitor cells and circulating endothelial cell, and investigate the damage and disorder mechanism of the vascular endothelial system in the patients with Graves. Methods The von Willebrand Factor antigen(vWF:Ag) was measured using the IL ACL-9000 blood coagulation instrument. The flow cytometry was used to measure the circulating endothelial cell（CEC）and endothelial progenitor cells（EPCs）. The free-triiodothyronine（FT3）and free thyroxin（FT4）were determined using the ADVIA Centaur chemiluminesent immunoassay analyzer. Results Compared the patients group with the control, the level of the vWF:Ag and CEC were increased obviously and EPCs was decreased remarkably in the Graves patients group（P<0.01）; CEC had no change（q＝1.35，P>0.05）, vWF:Ag（q＝21.77） was increased and EPCs（q＝8.89） was decreased siginficantly in the patients group(which had not combined with atrial fibrillation)（P<0.01）. Compared the Graves patients group(which had not combined with atrial fibrillation) with the patients group (which had combined with atrial fibrillation), vWF:Ag and CEC were increased（q＝19.92，q＝16.05）, EPCs was decreased significantly（q＝3.89）（P<0.01） in the patients group (which had combinated atrial fibrillation). There was strong positive relationship between FT3 and vWF:Ag, and negative relationship between FT3 and EPCs（P<0.01） in the patients group(which had not combinated atrial fibrillation); there was no relationship in the patients group (which had combinated atrial fibrillation). Conclusion There was the damage and dysfunction in the Graves patients, the decrease of the level of the EPCs led the ability of the vascular repair to weakness. Lots of the endothelial cell shed from the vascular wall, and the EPCs was lower in the patients which combined with atrial fibrillation, it made the extent of the damaged vascular endothelial more serious and the repair became more difficult., and it brought the worse thrombosis risk.

Key words: Graves, hyperthyroidism, endothelial progenitor cells, circulating endothelial cell, disorder