Oxidative stress in juvenile essential hypertension

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Abstract
Objective Oxidative stress, an antioxidant/pro-oxidant imbalance, in patients with juvenile essential hypertension was measured via several biochemical parameters. As the blood pressure is associated with the body mass index (BMI), results were compared with those on BMI-matched controls. Design and setting A prospective observational study at a university teaching hospital. Patients Children and adolescents with essential hypertension (mean ± standard deviation: age 14.4 ± 3.1 years, BMI 25.0 ± 6.9 kg/m2, n = 52) before any treatment, and controls with a similar BMI distribution (age 14.3 ± 4.3 years, BMI 24.4 ± 6.6 kg/m2, n = 48). Methods Measurements were made of the plasma levels of (1) nitrites + nitrates, an indirect measure of available nitric oxide; (2) lipid peroxidation end-products, as malondialdehydes and free thiols; and (3) the redox status of the red blood cell glutathione, as a new oxidative stress parameter. Results There were decreased plasma levels of nitrates and increased levels of lipid peroxidation end-products in the hypertensive patients, resulting in a consistent increase in the plasma lipid peroxidation/nitric oxide ratio as compared with the controls with the same BMI (P< 0.01). This ratio additionally correlated directly with both the systolic and diastolic blood pressures for the overall patient population (P< 0.001). A significant glutathione depletion in the red blood cells resulted in an elevated ratio of oxidized/reduced forms with a reduced in vitro antioxidant protective capacity in the hypertensive patients versus the BMI-matched controls (P< 0.001). Conclusions The presence of systemic oxidative stress was proven in hypertensive children and adolescents, irrespective of their BMI.