- 作者：Anna G. Dagre ; John P. Lekakis ; Athanassios D. Protogerou ; Gerassimos N. Douridas ; Theodoros G. Papaioannou ; Dimitrios J. Tryfonopoulos ; Christos M. Papamichael ; Maria Alevizaki
- 关键词：Subclinical hypothyroidism ; Endothelial dysfunction ; Cardiovascular disease ; Reactive hyperemia
- 刊名：International Journal of Cardiology
- 出版年：2007
- 期刊代码：128_01675273
- 类别：med
- 出版时间：18 January 2007
- 卷：114
- 期：3
- 页码：332-338
- 文件大小：193 K
It has been suggested that hypothyroidism is associated with an increased risk for cardiovascular disease. The aim of this study was to assess non-invasively NO-dependent endothelial function of resistance arteries in subjects with hypothyroidism of varying severity.
Methods
Ninety-six female subjects (aged: 42 ± 13 years) comprised the study population. Subjects were divided into five groups based on TSH levels at presentation: Group 0 (n = 23) with TSH: 0.3–2.0 μU/ml, Group 1 (n = 22) with TSH: 2.1–4.0 μU/ml (upper normal), Group 2 (n = 18) with TSH: 4.1–10 μU/ml (subclinical hypothyroidism), Group 3 (n = 22) with TSH > 10 μU/ml (overt hypothyroidism). One additional group with well-controlled hypothyroidism on l-thyroxine therapy (Group 4, n = 11, TSH: 0.3–2.0 μU/ml) was also studied. Endothelial function of resistance arteries was assessed by measuring forearm blood flow response during reactive hyperemia utilizing venous occlusion strain-gauge plethysmography.
Results
Duration of reactive hyperemia was significantly different among groups of subjects with varying hypothyroidism (83.7 ± 58.3 s, 53.2 ± 35.7 s, 52.8 ± 47.5 s, 12.9 ± 13.3 s and 69.5 ± 26.2 s in Groups 0, 1, 2, 3 and 4, respectively, p < 0.001, ANOVA). Duration of reactive hyperemia was significantly shorter in subjects with upper normal TSH values (Group 1) compared to controls (53.2 ± 35.7 s vs. 83.7 ± 58.3 s, p = 0.013), while it was comparable to that of subjects with subclinical hypothyroidism (Group 2) (52.8 ± 47.5 s). However, duration of reactive hyperemia in Group 1 was significantly longer compared to Group 3 (overt hypothyroidism) (53.2 ± 35.7 s vs. 12.9 ± 13.3 s, p = 0.002). Similarly, duration of reactive hyperemia in subjects with subclinical hypothyroidism was significantly longer compared to subjects with overt hypothyroidism (52.8 ± 47.5 s vs. 12.9 ± 13.3 s, p = 0.003). Duration of reactive hyperemia in Group 4 (well-controlled hypothyroidism on l-thyroxine therapy) did not differ significantly compared to controls. There was a highly significant linear correlation between duration of reactive hyperemia and TSH (r = − 0.383, p < 0.001).
Conclusion
Endothelial dysfunction was detected in the microvasculature of patients with hypothyroidism. Duration of reactive hyperemia decreased with increasing TSH levels. Since endothelial dysfunction is a factor leading to atherosclerosis, this abnormality may partly explain predisposition of patients with thyroid failure to cardiovascular disease.