Role of Serum Retinol Binding Protein 4 (RBP4) Concentration in Patients with Primary Hypertension: A Case-control Study

Abstract

Introduction: Serum Retinol Binding Protein 4 (RBP4), an adipokine that transports vitamin A from the liver to other tissues, is reported to be elevated in hypertensive subjects. Positive correlation between RBP4 and cardiovascular risk factors has been noted in a few studies. Aim: To evaluate serum RBP4 levels in newly diagnosed primary hypertensive cases and non hypertensive controls and to correlate serum RBP4 levels with lipid profile. Materials and Methods:This case-control study was conducted at the Department of Biochemistry in collaboration with the Department of Medicine, from August 2019 to June 2020 in MKCG Medical College and Hospital, Berhampur, Odisha, India. A total of 51 newly diagnosed primary hypertensive patients and 51 healthy age and sex-matched individuals between the ages of 18 to 50 years were enrolled in the study. Systolic and Diastolic Blood Pressure (SBP and DBP) were measured in both cases and controls.Serum RBP4 was measured by Enzyme-Linked Immunosorbent Assay (ELISA) and other biochemical parameters were measured by TBA120FR autoanalyser. Result: The mean age for controls was 36.98±8.7 years and that in cases was 39.00±8.4 years. Proportion of males was higher (56.8%) than females (43.2%). The mean systolic blood pressure in the case group was significantly higher as compared to the control group. The cases had a higher level of serum RBP4 (31.82 mg/L) compared to the control groups (15.5 mg/L) RBP4 (p<0.001). The cases had a higher level of mean serum triglyceride (196.20±67.81 mg/dL) and lower level of mean serum High-Density Lipoprotein cholesterol (HDLc) (37.53±11.90 mg/dL) as compared to the control groups which had a mean triglyceride of 104.25±39.89 mg/dL and HDLc of 57.18±10.73 mg/dL (p<0.001). The serum RBP4 level positively correlated with SBP (r=0.644, p<0.001), DBP (r=0.444, p<0.001), serum triglycerides (r=0.649, p<0.001), and negatively correlated with HDLc (r=-0.313, p=0.025). Conclusion: A high serum RBP4 level was found in the newly diagnosed hypertensive cases as compared to normotensive controls. A significant positive correlation was observed between RBP4 with systolic and diastolic blood pressure along with triglyceride levels. A significant negative correlation was observed between RBP4 with HDLc.