Abstract

MASKIN DE JENSEN, A. et al. Relationship between serum leptin levels and sodium excretion in a local population of obese children and adolescents. Rev. argent. endocrinol. metab. [online]. 2011, vol.48, n.3, pp.127-135. ISSN 1851-3034.

Obesity is associated with elevated levels of leptin and most obese individuals are "selectively" resistant to its metabolic action, without appetite loss or increased energy expenditure, with preservation and stimulation of the activation of the sympathetic system at both the central and peripheral cardiovascular and renal levels. These mechanisms could modify the regulation of sodium metabolism in the kidney. Objective: To determine whether there is any correlation among between serum leptin levels and urinary sodium excretion in a population of obese children and adolescents an obese, children and adolescents. Material and methods: 190 children and adolescents between 5 and 15 years of age were studied: 125 with body mass index (BMI) = 95 percentile constituted the obese group (OB) and 65 with BMI percentile 5 - < 85 the control group (C). Concentrations of serum sodium (Na) and urinary sodium (Nao) were measured with ion selective electrode; serum leptin levels were measured by the immunoradiometric method. Results: Differences between groups were significantly lower for urinary sodium values (mEq/kg/day) in obese subjects compared with controls for both sexes and in different age groups. The obese population has higher leptin/BMI (ng/ml/IMC) and lower concentrations of urinary sodium in the different groups/subgroups: OB girls 5 to 9 years of age Nao 2.69 ± 0.19, leptin/BMI 0.63 ± 0.06; OB girls 10 to 15 years Nao 2.20 ± 0.17, leptin/BMI 1.11± 0.12; OB boys 5 to 9 years Nao 2.07± 0.16, leptin/BMI 0.80 ± 0.15; OB boys 10 to 15 years Nao 2.57 ± 0.23, leptin/BMI 0.65 ± 0.09. Our study suggest that elevated serum leptin levels, typical of conditions such as obesity, may contribute to alterations in sodium metabolism, due to decreased urinary excretion of this ion.

Keywords : Leptin; Sodium excretion; Obesity, Children and adolescents.

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