The Relationship Between Leptin and Norepinephrine Levels During OGTT in Normotensive and Hypertensive Obese Adolescents

Background/Aims: Studies in adult population have suggested that leptin might play a role in inducing obesity related hypertension mediated by the sympathetic nervous system. This association has not been established for adolescents. Our study is designed to explore the relationship between leptin and norepinephrine levels in pediatric patients and to identify any contributors to hypertension for this population.
Methods: Thirty-nine obese adolescents, divided into four groups by gender and hypertension status were included in the study. Leptin and norepinephrine levels were measured during oral glucose tolerance tests (OGTT) to optimize hormonal secretion. T tests were used to compare baseline levels of glucose, insulin, leptin and norepinephrine at 0 hour point of OGTT between the hypertensive and normotensive patients for both genders. Analysis of covariance (ANCOVA) was used for comparison of subsequent levels between the hypertensive and normotensive groups for in both genders, with the corresponding baseline level as the covariance. Models with and without BMI adjustment were created and their results were found to be consistent. Correlation between leptin and norepinephrine was examined at each time point and through analysis of area under the curve (AUC).
Results: Contrary to the previous findings obtained in adult patients, our results did not show any direct relationships between levels of leptin and norepinephrine. A slight decrease in norepinephrine level at 1 hour in the normotensive male group and a significant increase in leptin level at 1 hour in the hypertensive female group was observed.
Conclusion: Our preliminary data suggest that norepinephrine and leptin levels at 0 and 1 hour during routine OGTT, for males and females, respectively, may help identify a subgroup of obese adolescents who have higher risk for hypertension and cardiovascular complications.