The relationship between apelin and cardiac parameters in patients on peritoneal dialysis: is there a new cardiac marker?

Background: Many markers have been proposed for CVD risk assessment in dialysis population. Apelin is a peptide that has roles in cardiovascular functions and volume regulation namely vasodilation, decreased blood pressure (BP), positive inotropic effect and inhibition of antidiuretic hormone release. The aim of this study was to examine relationship of apelin levels with echocardiographic findings and laboratory parameters related with cardiovascular function and bone mineral metabolism among peritoneal dialysis (PD) patients. Methods: This is a cross-sectional study in which chronic PD patients aged between 18 and 80 without active cardiac, infectious or malignant diseases and hypervolemia have been included. Apelin-36 levels and echocardiographic findings were recorded as well as clinical and laboratory data. Results: Of the 53 patients, the mean age and female/male ratio was 52.8 +/- 15.3 years and 30/23, respectively. Mean apelin level was 1.45 +/- 0.37 ng/ml. Gender, drugs (renin-angiotensin-aldosteron inhibitors, statins), presence of left ventricular hypertrophy, diabetes mellitus, hypertension, hyperlipidemia and significant residual renal function did not affect apelin-36 levels. Apelin-36 was correlated negatively with age and left atrium diameter; and positively with diastolic BP, ejection fraction (EF), total cholesterol, LDL-cholesterol, HDL-cholesterol, parathyroid hormone and alkaline phosphatase (ALP) levels. Diastolic BP, LDL-cholesterol, ALP and EF were found to be the independent determinants of apelin-36 levels with linear regression analysis. Conclusions: Apelinergic system has important roles in volume regulation, cardiovascular functions, lipid metabolism and bone mineral disorders in PD patients. Prospective studies with large population are required.