Hypertension is increasingly common in overweight and obese children. The mechanisms behind the development of hypertension in obesity are complex, and evidence is limited. In order to effectively treat obese children for hypertension, it is important to have a deeper understanding of the pathophysiology of hypertension in obese children. The present review summarizes the main factors associated with hypertension in obese children and discusses their potential role in its pathophysiology. Systematic searches were conducted in PubMed and EMBASE for articles published up to October 2014. In total, 60 relevant studies were included. The methodological quality of the included studies ranged from weak to strong. Several factors important in the development of hypertension in obese children have been suggested, including endocrine determinants, such as corticosteroids and adipokines, sympathetic nervous system activity, disturbed sodium homeostasis, as well as oxidative stress, inflammation and endothelial dysfunction. Understanding the pathophysiology of hypertension in overweight and obese children is important and could have implications for its screening and treatment. Based on solely cross-sectional observational studies, it is impossible to infer causality. Longitudinal studies of high methodological quality are needed to gain more insight into the complex mechanisms behind the development of hypertension in obese children.

Objective:The precise mechanisms behind the development of hypertension in overweight or obese children are not yet completely understood. Alterations in hypothalamic-pituitary-adrenal axis activity may play a role. We aimed to investigate the association between cortisol parameters and hypertension in overweight or obese children.Methods:Random urine (n=180) and early-morning saliva samples (n=126) for assessment of cortisol and cortisone were collected from 1) hypertensive overweight children (n=50), 2) normotensive overweight children (n=145), and 3) normotensive non-overweight children (n=75).Results:The age of participants was 10.4±3.3 years and 53% were boys. The urinary cortisol-to-cortisone ratio [β 1.11, 95% confidence interval (CI) 1.05-1.19] as well as urinary cortisol/creatinine (β 1.38, 95% CI 1.09-1.54), and cortisone/creatinine ratios (β 1.26, 95% CI 1.17-1.36) were significantly higher in overweight or obese than in non-overweight children. After adjusting for body mass index-standard deviation score and urinary cortisone/creatinine ratio, but not cortisol/creatinine ratio, was significantly associated with presence of hypertension (β 1.12, 95% CI 1.02-1.23). Salivary cortisol and cortisone levels were significantly lower in overweight or obese than in non-overweight children (β -4.67, 95% CI -8.19- -1.15, and β 0.89, 95% CI 0.80-0.97 respectively). There were no significant differences in cortisol parameters between hypertensive and normotensive overweight or obese children.Conclusion:This study provided further evidence for an increased cortisol production rate with decreased renal 11β-hydroxysteroid dehydrogenase 2 activity and flattening of early-morning peak cortisol and cortisone in overweight or obese children. However, there were no significant differences in cortisol parameters between hypertensive and normotensive overweight and obese children.

Objectives The aim of this study is to explore different methods for screening and diagnosing hypertensionwhich definitions and criteria to use-in children and in addition to determine the prevalence of hypertension in Dutch overweight children. Design A cross-sectional study performed in the Dutch Child Health Care setting. Setting Four Child Health Care centres in different cities in the Netherlands. Participants 969 overweight (including obese) and 438 non-overweight children, median age 11.7 years (range 4.1-17.10), 49% boys. Main outcome measures The main outcome was blood pressure, and the difference in prevalence of hypertension using different criteria for blood pressure interpretation: using the first blood pressure measurement, the mean of two measurements and the lowest of three measurements on two different occasions. Results Looking at the first measurement alone, 33% of overweight and 21% of non-overweight children had hypertension. By comparing the mean of the first two measurements with reference values, 28% of overweight children and 16% of non-overweight children had hypertension. Based on the lowest of three consecutive measurements, the prevalence decreased to 12% among overweight children and 5% among non-overweight children at visit one and at visit two 4% of overweight children still had hypertension. Conclusions The prevalence of hypertension is highly dependent on the definitions and criteria used. We found a prevalence of 4% in overweight children, which is considerably lower than suggested by recent literature (4%-33%). This discrepancy can be explained by our more strict definition of hypertension. However, to draw any conclusions on the prevalence, normal values using the same definition of hypertension should be established. Despite the low prevalence, we recommend measuring blood pressure in all overweight children in view of later cardiovascular morbidity and mortality.

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