The apelinergic system plays an important role in the modulation of the cardiovascular system via the apelin peptide and the apelin receptor (APJ receptor). Apelin and elabela, also known toddler, are peptide ligands for the apelin receptor. These two peptides show similar biological actions, such as vasodilatation, increased myocardial contractility, angiogenesis, and energy metabolism. However, the serum levels of elabela in patients with hyperthyroidism are not well known. The aim of this study was to investigate the changes in serum elabela levels in patients with hyperthyroidism and its association with hypertension. This cross-sectional study included 74 patients with newly diagnosed hyperthyroidism due to Graves' disease and 20 healthy individuals. Serum elabela levels were measured by enzyme-linked immunosorbent assay. The patients were divided into two groups: hyperthyroid patients without hypertension (n = 51) and those with hypertension (n = 23). Basal heart rate, serum glucose and high-sensitive C reactive protein were significantly higher in hyperthyroid patients with and those without hypertension than in healthy controls (p < 0.05 for each). Serum elabela levels were significantly elevated in hyperthyroid patients compared with healthy controls, with higher serum elabela levels found in hyperthyroid patients with hypertension than those without hypertension. Linear regression analysis showed that serum elabela levels were correlated with systolic blood pressure (p < 0.001). In conclusion, serum elabela levels were significantly increased in patients with hyperthyroidism, especially in hyperthyroid patients with hypertension. Elevation in serum elabela levels may contribute to alleviation of cardiovascular complications of hyperthyroidism and hypertension.
Keywords: apelinergic system; elabela; hypertension; hyperthyroidism; systolic blood pressure.