PurposeElevated plasma concentration of retinol binding protein 4 (RBP4) has recently emerged as a potential risk factor as a component of developing metabolic syndrome (MS). Therefore, this study aimed to analyse the relationship between components of MS and concentrations of plasma RBP4 in a population of subjects 65 years and older.MethodsThe study sample consisted of 3038 (1591 male) participants of the PolSenior study, aged 65 years and older. Serum lipid profile, concentrations of RBP4, glucose, insulin, C-reactive protein, IL-6, and activity of aminotransferases were measured. Nutritional status (BMI/waist circumference) and treatment with statins and fibrates were evaluated. Glomerular filtration rate (eGFR), de Ritis ratio, and fatty liver index (FLI), as well as HOMA-IR were calculated.ResultsOur study revealed a strong relationship between components of MS and RBP4 in both sexes: plasma RBP4 levels were increased in men by at least 3×, and in women by at least 4×. Hypertriglyceridemia was most strongly associated with elevated plasma RBP4 levels. Multivariate, sex-adjusted regression analysis demonstrated that chronic kidney disease [OR 1.86 (95% CI 1.78–1.94)], hypertriglyceridemia [OR 1.52 (1.24–1.87)], hypertension [OR 1.15 (1.12–1.19)], low serum HDL cholesterol [OR 0.94 (0.92–0.97)], and age > 80 years [OR 0.86 (0.81–0.90)] were each independently associated with RBP4 concentration (all p < 0.001).ConclusionsIn Caucasians 65 years and older, RBP4 serum levels are associated with a number of components of MS, independent of sex and kidney function. Hypertriglyceridemia as a component of MS is most significantly related to RBP4 concentration.

Background/Aim: Elevated plasma concentration of retinol-binding protein 4 (RBP4) has recently emerged as a potential new risk factor for cardiovascular diseases, including hypertension (HT) and coronary artery disease (CAD). Limited data suggest that RBP4 promotes inflammatory damage to cardiomyocytes and participates in the development of heart failure (HF). This study aimed to analyze the relationship between concentrations of plasma RBP4 and serum N-terminal proBNP (NT-proBNP), a powerful biomarker of left ventricle dysfunction, in the older Polish population. Methods: The study sample consisted of 2,826 (1,487 men) participants of the PolSenior study, aged 65 years and older, including a subgroup hospitalized for HF (n = 282). In all subjects, plasma concentrations of RBP4, interleukin-6 (IL-6), serum level of NT-proBNP, and hs-CRP were measured. Additionally, BMI, estimated glomerular filtration rate (eGFR), and HOMA-IR were calculated. The prevalence of HT, CAD, atrial fibrillation (AF), and medication were considered as potential confounders. Results: Similar RBP4 levels were found in subjects with NT-proBNP < 125 and ≥125 ng/mL, with and without AF, and in the subgroups hospitalized for HF with and without AF. Regression analysis revealed no association between log₁₀(NT-proBNP) and log₁₀(RBP4). Plasma levels of RBP4 were increased by HT occurrence and diuretic therapy, while diminished with regard to female gender, age, eGFR values, AF, and IL-6 levels. Conclusion: Our results show that RBP4 is affected by GFR but cannot be considered as an independent biomarker of heart muscle dysfunction.

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