Evaluating Serum Apelin and Nitric Oxide in Primary Hypertensive Patients with or without Microalbuminuria: A Cross-sectional Study

Abstract

Introduction: Hypertension (HTN) is the third leading risk factor contributing to the disease burden in Southeast Asia. Understanding its underlying mechanism, such as endothelial dysfunction, is very important. Apelin is a recently discovered endogenous peptide hormone that, along with Nitric Oxide (NO), is implicated in endothelial dysfunction and the severity of HTN. This can significantly reduce renal function and lead to microalbuminuria/proteinuria in 5-15% of patients. Aim: To measure serum apelin and NO in patients with newly diagnosed primary HTN with or without microalbuminuria and to investigate the correlation of serum apelin with HTN in the same study population. Materials and Methods: This cross-sectional study was conducted from February 2019 to January 2021 in the Department of Biochemistry In collaboration with the Department of Medicine at SCB Medical College and Hospital, Cuttack, Odisha, India. A total of 180 participants were included in the present study. Among them, 90 were newly diagnosed hypertensive patients, and 90 were non hypertensive. The study comprised of 90 hypertensive patients, with 46 having microalbuminuria (Group-A), 44 without microalbuminuria (Group-B) and 90 normotensive controls (Group-C). All participants underwent evaluation of their biochemical profile which included Fasting Plasma Sugar (FBS), serum urea, creatinine, Total Cholesterol (TC), Triglyceride (TG), High-density Lipoprotein cholesterol (HDL-c), Low-density Lipoprotein cholesterol (LDL-c), Very Low-Density Lipoprotein (VLDL), serum apelin and NO levels, and urine albumin. The comparison between the three groups was done by using Analysis of Variance (ANOVA) test with post-hoc analysis. The Chi-square test was used to compare categorical variables. Results: The mean age of the participants was 50.48±9.73 years. study comprised of 90 hypertensive patients, with 46 having microalbuminuria, 44 without microalbuminuria, and 90 normotensive controls. The mean serum apelin levels were 394.45±84.2, 386.9±86.12, and 62.73±22.87 ng/L, respectively, among patients with microalbuminuria, without microalbuminuria, and normotensive patients. Similarly, the mean serum NO levels were 6.31±2.94, 8.32±2.63, and 20.15±4.37 µmol/L, respectively, among the three groups. The comparison of mean values indicated a significant (p<0.001) positive correlation between the level of serum apelin and HTN and its complications, such as microalbuminuria. Conclusion: The positive correlation between serum apelin levels and blood pressure underscores the potential role of apelin in hypertensive pathophysiology.