Angiopoietin-2: a biomarker in hyperthyroidism

Abstract

Serum angiopoietin-2 level is elevated in several diseases suggesting its possible role as a mediator of angiogenesis and vascular network remodeling. Triiodothyronine and thyroxine have well documented effects on angiogenesis in vitro, but only few reports have studied angiopoietin-2 in thyroid-disease patients. The aim of the present study was to measure soluble angiopoietin-2 serum levels in a group of thyroid-disease patients with different levels of free triiodothyronine and thyroxine. Angiopoietin- 2 were quantified by ELISA in sera of fifteen healthy volunteers and forty-two thyroid ambulatory patients: nine with hyperthyroidism, four in therapy for hyperthyroidism, seven with subclinal hyperthyroidism, twelve with hypothyroidism, five with thyroiditis and five in therapy for thyroiditis. Median angiopoietin-2 level was significantly elevated in hyperthyroid patients (p < 0.01) and it was significantly increased vs all the other groups (p < 0.0001). In hyperthyroid patients anti thyroid therapy seems to reduce angiopoietin-2 level. A significant positive correlation was observed between Log angiopoietin-2 levels and serum concentration of Log free triiodothyronine (r = 0.4, P < 0.001) and Log free thyroxine (r = 0.4, P < 0.001) respectively. In conclusion, increased levels of angiopoietin-2 are present in hyperthyroid patients, and seems to correlate with free triiodothyronine and free thyroxine levels but not with anti-thyroid antibodies. These findings suggest angiopoietin-2 as a mediator of angiogenesis and vascular network remodeling in this disease, but further studies will be needed to determine the role of this biomarker in the pathophysiology and progression of hyperthyroidism.

Keywords: Angiogenesis; Angiopoietin-2; Hyperthyroidism; Hypothyroidism; Thyroid hormons.