Metabolic syndrome in children and adolescents: Classification, risk factors and health impact
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The metabolic syndrome in children and adolescents is considered as a cluster of cardiovascular risk factors that have a substantial health impact not only during the childhood and adolescent years, but also tracking into adulthood. Diagnosis of the metabolic syndrome in youth is confusing, since an array of classifications have been used, all coinciding in the risk factors, but differing mainly in the cut-off points. With the purpose of unifying criteria, the International Diabetes Federation established a classification in 2007 with cut-off values corresponding to those of adults; this differs from the rest of the classifications which use values depending on age and sex. There is still no universally accepted definition of the metabolic syndrome in children and adolescents. Criteria for the diagnosis include: elevated waist circumference or other measure of obesity, hypertension, hypertrigliceridemia, low high-density cholesterol and hyperglycemia or insulin resistance. The prevalence of the metabolic syndrome in children and adolescents varies greatly not only because of the country and populations studied, but because of the use of many different definitions. Risk factors for the metabolic syndrome include: heredity, ethnicity, inflammation, oxidative stress, fiber consumption, physical activity, vitamin D deficiency, insulin resistance and obesity. Regarding hereditability, children of parents with the metabolic syndrome may be at especially high risk because of genetic factors. Ethnic differences also contribute; Hispanics and blacks being particularly predisposed to alterations in one or more components of the syndrome. Inflammatory and prothrombotic adiopocytokines and cytokines, such as adiponectin, C-reactive protein, interleukin-6, tumor necrosis factor-alfa, cortisol, as well as oxidative stress also play a part. Besides, children with vitamin D deficiency are more prone to develop metabolic syndrome. But, above all, obesity, especially abdominal/visceral obesity, is the primary risk factor for development of the metabolic syndrome, its prevalence increasing according to the degree of obesity. Lifestyle behaviors have also been implicated in the development of the metabolic syndrome; increased consumption of whole grains foods improves insulin sensitivity and inflammation and decreases the development of coronary heart disease, diabetes and the metabolic syndrome, while consumption of saturated fat and cholesterol have a negative impact. Physical activity has a positive effect too on insulin resistance and some of the components of the metabolic syndrome. The health impact during childhood is striking and it is well known that it tracks into adulthood. Obese children have a 2 to 4 fold higher risk of hypertension and an approximately 4 fold higher risk of hyperlipidemia and type 2 diabetes. The metabolic syndrome in children and adolescents has been strongly associated with insulin resistance and conveys a heightened risk for early atherosclerotic cardiovascular disease and type 2 diabetes mellitus, and predicts the likelihood of cardiovascular events in adults by 2 to 3 times fold. The metabolic syndrome has also been positively associated with proinflammatory and inflammatory cytokines, adipocytokines, increased oxidative stress, impaired endothelial function, increased arterial stiffness, carotid artery intima-media thickness, a preponderance of small, dense low density lipoprotein particles, vitamin D deficiency, as well as increased cortisol and uric acid levels. Other diseases related to the syndrome are nonalcoholic fatty liver disease, progressive to cryptogenic cirrhosis, hyperandrogenism and polycystic ovary syndrome. Stress and depression have also been positively associated. The health impact of the metabolic syndrome in children and adolescents highlights the need for effective strategies to prevent and halt the progression of the syndrome. © 2012 by Nova Science Publishers, Inc. All rights reserved.