Endothelial Dysfunction in Hyper- and Hypo-Thyroidism.

Objective: To investigate endothelin-1 (ET-1) and several other endothelial function parameters in hyper and hypo-thyroidism. Patients and methods: Thirty-five hyperthyroid, 11 hypothyroid and 35 euthyroid patients were evaluated for von Willebrand factor activity (vWf), plasma fibronectin and ET-1. Non-parametric tests were used for statistical analysis. Results: Significantly elevated plasma levels of endothelin-1 and fibronectin (30.08 ± 11.21 pmol/L; 37.9 ± 6.5 mg/dl) were measured in hyperthyroid patients compared to controls (22.91 ± 7.51 pmol/L; 32 ± 7.5 mg/dl), (p = 0.011; p = 0.001, respectively) but only fibronectin compared to hypothyroids (25.55 ± 12.65 pmol/L; 29.28 ± 9.9 mg/dl) (p = 0.271; p = 0.006, respectively). Positive correlations were found between ET-1 and free-triiodothyronine (r = 0.320; p = 0.009) and free-thyroxine (r = 0.271; p = 0.029); and between ET-1 and heart rate (r = 0.278, p = 0.027) in the whole sample. Positive correlation was also observed between vWf and free-triiodothyronine (r = 0.283; p = 0.017). Conclusion: The role of shear stress and/or direct effects of thyroid hormones were thought to be the possible causes of elevated levels of ET-1 and fibronectin in hyperthyroidism. Ann Med Sci 2003;12:79-84. [ABSTRACT FROM AUTHOR]