ORIGINAL ARTICLE Serum Apelin Levels and Ascending Aortic Aneurysm in Adults Mihriban Yalcin 1 & Gündüz Yumun 2 & Ahsen Yilmaz 3 & Hakan Kalafat 4 & Savaş Guzel 3 Received: 6 March 2020 /Accepted: 29 May 2020 # Association of Surgeons of India 2020 Abstract Apelin is a peptide isolated from bovine stomach and has vasodilator and inotropic activities. The aim of this study was to confirm the relationship between serum apelin levels and ascending aortic dilatation in adult patients. This study included 39 patients with ascending aortic aneurysm who applied to the cardiovascular surgery outpatient clinic between 1 June 2019 and 31 August 2019 and 50 healthy volunteers. Serum apelin and serum apelin receptor levels were measured with ELISA method. Serum apelin levels were lower in patients with aortic aneurysm compared to the control group, while serum apelin receptor levels were higher. These findings may show that serum apelin and apelin receptor levels may be a potential biomarker for aortic aneurysm. Keywords Adult . Ascending aortic aneurysm . Apelin . Apelin receptor Introduction An aneurysm is defined as a local and permanent expansion in any aortic segment at least 50% of the expected diameter. However, ascending aortic diameter varies according to gen- der and body mass; it is <4 cm, and fusiform aneurysms are most common, and it is most commonly located in supracoronary location. It has fatal complications such as rup- ture and dissection. Therefore, early diagnosis and treatment are of great importance. Apelin, an endogenous peptide, was identified as a ligand of the orphan G protein-coupled receptors. Apelin receptor (APJ) is a member of seven trans-membrane G protein- coupled receptor family [1]. The apelin/APJ system has many physiological effects, such as fluid and glucose homeostasis, nutritional behavior, and immunity [2]. Our study focused on serum apelin and serum apelin recep- tor levels in aortic aneurysm. Thus, the purpose of this study was to assess the relationship between serum level of apelin and ascending aortic dilatation in adults. Methods This study complies with the Declaration of Helsinki and was approved by the Instituional Ethical Committee of Ordu University (Decision number: 2019–73), and all patients pro- vided informed consent for participation. The diagnosis of aneurysm was made based on transthoracic echocardiography and computed tomography arteriographies. Evaluation was made of 89 consecutive patients admitted to our polyclinic between 1 June 2019 and 31 August 2019. Patients with coronary artery disease and peripheral artery disease were excluded from the study. The study group included 39 patients with ascending aortic aneurysm, and the control group included 50 healthy volun- teers. The patients in the groups were comparable in terms of age, BSA, gender distribution, HDL (high-density lipoprotein) and LDL (low-density lipoprotein) cholesterols, and triglycerides (TG). A venous blood sample of 10 mL was obtained for the analysis of serum apelin levels. The samples were centrifuged at 2500×g for 10 min portioned into eppendorf tubes and stored at - 40 °C until analysis. Serum human apelin level was measured using ELISA kit (Elabscience Biotechnology Co. Ltd., USA). The measurement * Mihriban Yalcin mihribandemir33@hotmail.com 1 Cardiovascular Surgery, Ordu State Hospital, Sahincili Mah. Devlet Hastanesi, 52200 Ordu, Turkey 2 Cardiovascular Surgery, Namık Kemal University, Tekirdag, Turkey 3 Medical Biochemistry, Namık Kemal University, Tekirdag, Turkey 4 Medical Biochemistry, Ordu State Hospital, Ordu, Turkey Indian Journal of Surgery https://doi.org/10.1007/s12262-020-02440-3