Academic journal article Childhood Obesity

Waist Circumference Percentiles in Indigenous Argentinean School Children Living at High Altitudes

Academic journal article Childhood Obesity

Waist Circumference Percentiles in Indigenous Argentinean School Children Living at High Altitudes

Article excerpt

[Author Affiliation]

Valeria Hirschler. 1 Department of Pharmacology, University of Buenos Aires, Buenos Aires, Argentina.

Claudia Molinari. 1 Department of Pharmacology, University of Buenos Aires, Buenos Aires, Argentina.

Gustavo Maccallini. 2 Hidalgo Laboratories, Buenos Aires, Argentina.

Mariana Hidalgo. 2 Hidalgo Laboratories, Buenos Aires, Argentina.

Claudio Gonzalez. 1 Department of Pharmacology, University of Buenos Aires, Buenos Aires, Argentina.

Address correspondence to: Valeria Hirschler, MD, University of Buenos Aires, Department of Nutrition, Maipu 812 5 M, Buenos Aires (1006), Argentina, E-mail: vhirschler@intramed.net

Introduction

Developing countries are currently experiencing a higher prevalence of childhood obesity than ever before, and ethnic differences have been documented in this regard. Central obesity is also on the rise and is associated with increased risk for type 2 diabetes mellitus and cardiovascular disease.1 Waist circumference (WC) percentiles, one of the anthropometric measures related to central obesity, are strongly correlated with cardiovascular risk factors and have become widely used in children.2,3 This study was performed in San Antonio de los Cobres (SAC) and its suburbs, located in the Altiplano region of Argentina. The Altiplano region lies in the central Andes mountains, with an average height of approximately 3750 m above sea level, mean annual temperatures below 10° C, and total annual rainfall less than 1000 ml. Chronic hypoxia due to high altitudes has conditioned a series of adaptive changes, some of which are anthropometric changes.4 What is unclear is whether the environment, rather than genetic factors, mainly determines the phenotype of a high-altitude individual. Individuals living at high altitudes have raised hemoglobin concentration, enlarged lung volume, and blunted hypoxic ventilatory response, representing the successful human long-term adaptation to hypobaric hypoxia.

A previous study showed that Americans living at <500 m above sea level had approximately five times the risk of obesity compared with counterparts living >3000 m above sea level,5 suggesting that reduced temperature at increased elevation may lead to weight loss through catabolic effects. Consistently, a large study found regional differences in BMI upon preliminary examination of state-level US maps published by the CDC.6 Accordingly, a study performed in this community showed that Argentinean indigenous children living at high altitudes had significantly higher mean hemoglobin levels and lower prevalence of obesity than mixed population Argentinean children living at sea level.7 Mechanisms relating elevation and obesity include hypoxia, leptin signaling, metabolic demands, norepinephrine levels and fetal/childhood growth. Hypoxia may modulate leptin levels through the hypoxia-inducible transcription factor, which regulates both iron metabolism and leptin gene expression.8

Percentile reference charts are commonly used in pediatrics and can be used to screen children for appropriate growth by comparisons with those of the same age and sex. WC percentiles have been developed for children and adolescents in many countries.9-12 However, most studies in children have been limited to Western countries and infrequently include children from American indigenous populations. Indigeneous Koya children are generally not included in national surveys that monitor health status, or the numbers are too small to draw meaningful conclusions. Data, when available, are self-reported. No data are available for WC percentiles and their association with cardiovascular risk from a large population of Koya children. To our knowledge, no previous study has developed WC reference data for indigenous Koya children according to age and gender. …

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