Relationship between serum copeptin levels and non-invasive endothelial function indicators in dipper and non-dipper hypertensive patients

Abstract

Objective: Pathological changes in the endothelium are the earliest determinants of endothelial dysfunction and atherosclerosis in hypertension (HT). The diagnostic and prognostic role of copeptin in various diseases is well-recognized. This study aims to investigate the relationship between serum copeptin levels and non-invasive endothelial function indicators determined by flow-mediated dilation (FMD) and pulse wave analysis (PWA) in dipper and non-dipper HT patients.

Methods: In this study, 30 dipper HT, 31 non-dipper HT patients and 30 healthy control subjects were included. Blood samples were taken for copeptin level determination. All participants underwent detailed cardiovascular and transthoracic echocardiography examinations and measurements of FMD and PWA.

Results: Copeptin levels of the non-dipper HT group were significantly higher than the control group and dipper HT groups (P=.001, P=.010, respectively). No significant difference was found between the dipper and non-dipper HT groups regarding FMD and PWA measurements, and both groups significantly differed from the control group. In the whole group evaluation by partial correlation analysis, a significant correlation was found between serum copeptin levels and reflection index (RI) after adjustment for age and body mass index (r=0.24, P=.039). Stepwise linear regression analysis revealed RI as an independent predictor of copeptin (β=0.285, P=.015).

Conclusion: The correlation between copeptin levels and RI in HT patients, especially in the non-dipper HT group, suggests that copeptin can be used as a biomarker to indicate endothelial dysfunction in hypertensive patients.

Keywords: Arginine vasopressin; arterial stiffness; copeptin; endothelium; flow-mediated dilation; hypertension; pulse wave analysis.

Figure 1

Digital Volume Pulse (DVP) waveform obtained through pulse wave analysis (PWA). The waveform of the first pulse generated by blood pressure on the vessel wall in PWA is defined as a and the waveform of the reflection pulse of the first pulse depending on the tone of the vessel wall is defined as b. The time difference between the waveforms of b and a is defined as pulse propagation time (PPT). Stiffness index = a/PPT, Reflection index = b/a.

Figure 2

Graph showing the difference of copeptin levels as ng/mL among groups.

Figure 3

Correlation between copeptin levels and reflection index.