Changes in endothelium-dependent arterial dilation before and after subtotal thyroidectomy in subjects with hyperthyroidism.
OBJECTIVE
This case-control study was carried out to assess the alteration of endothelium-dependent arterial dilation before and after subtotal thyroidectomy in subjects with hyperthyroidism.


METHODS
The study subjects included 12 patients with hyperthyroidism and 39 apparently healthy individuals. We performed a subtotal thyroidectomy on the hyperthyroid patients. The endothelium-dependent arterial dilation was determined with a high-resolution ultrasound method in each patient at the hyperthyroid stage before treatment (stage H), the euthyroid stage induced immediately before surgery (stage E), and the transient hypothyroid stage 1 or 2 months after surgery (stage L).


RESULTS
The flow-mediated arterial dilation decreased significantly from H to E and from E to L (P < 0.001). As compared with H, baseline blood flow decreased markedly at stages E and L (P < 0.001). The flow-mediated arterial dilation and baseline blood flow in the control subjects were very close to those at stage E of the hyperthyroid patients. The absolute change in the flow-mediated arterial dilation showed significant negative correlation with the changes in TSH (r =-0.86, P < 0.001), lipoprotein (a) [Lp(a)] (r =-0.77, P < 0.001) and low density lipoprotein (LDL) (r =-0.79, P < 0.001), and significant positive correlation with changes in fT3 (r =+0.88, P < 0.001). The absolute change in the baseline blood flow showed significant positive correlation with the change in fT3 (r =+0.85, P < 0.001) and significant negative correlation with the change in TSH (r =-0.63, P < 0.01).


CONCLUSIONS
The endothelium-dependent arterial dilation increases significantly in untreated hyperthyroid patients, and decreases markedly after a subtotal thyroidectomy. Therefore, we conclude that the endothelium is more responsive to reactive hyperaemia in the hyperthyroid than the euthyroid state.
Guang-da
Xiang
X
Department of Endocrinology, Guangzhou Command Wuhan General Hospital of PLA, Wuhan, Hubei Province, PR China. Guangda64@163.net
Hong-yan
Cao
C
Xian-mei
Zeng
Z
D000328:Adult; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D016022:Case-Control Studies; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000000981:diagnostic imaging / Q000378:metabolism / Q000601:surgery*; D017270:Lipoprotein(a) / Q000032:analysis; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D011184:Postoperative Period; D012039:Regional Blood Flow; D018709:Statistics, Nonparametric; D013965:Thyroidectomy; D013972:Thyrotropin / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014463:Ultrasonography; D014664:Vasodilation
D017270:Lipoprotein(a); D008077:Lipoproteins, LDL; D014284:Triiodothyronine; D013972:Thyrotropin