Metabolic syndrome in Turkish children and adolescents

Abstract

The aim of this study was to determine the prevalence and phenotype of metabolic syndrome in Turkish children and adolescents. We adapted the National Cholesterol Education Program Adult Treatment Panel III criteria of metabolic syndrome to children and adolescents. Using the international cutoff points and percentiles, we determined 10- to 17-year-old Turkish children and adolescents with high blood pressure, high triglyceride (TG), low high-density lipoprotein cholesterol (HDL-C), fasting glucose of 100 mg/dL or greater, and elevated body mass index corresponding to overweight or obesity. We examined 1385 apparently healthy students between the ages of 10 to 17 years from Ankara, Turkey: 4.9% of the subjects were overweight or obese; 29.2% had either low HDL-C and/or high TG levels; and 15.7% had either systolic or diastolic blood pressure above the 95th age-, sex-, and height-specific percentile. Thirty students (2.2%) had metabolic syndrome by having 3 or more risk variables. Metabolic syndrome was nearly 10 times more common among overweight and obese students (21%), compared with lean students. Components of metabolic syndrome such as high blood pressure and high TG, and low HDL-C levels were common among Turkish children and adolescents. Strategies should focus on early detection and treatment of these risk variables in Turkish children.

Introduction

Metabolic syndrome represents a constellation of lipid and nonlipid cardiovascular risk factors of metabolic origin [1], [2]. Individuals with metabolic syndrome are at risk for type 2 diabetes mellitus [3] and cardiovascular disease [4]. The World Health Organization [1] and National Cholesterol Education Program (NCEP) Adult Treatment Panel III [2] define metabolic syndrome in adults. These definitions carry certain differences; NCEP definition is based on the number of risk factors, among which are abdominal obesity, elevated triglycerides (TGs) (>150 mg/dL), low high-density lipoprotein cholesterol (HDL-C) (<40 mg/dL in men and <50 mg/dL in women), blood pressure (≥130/85 mm Hg), and elevated fasting glucose (≥110 mg/dL). Having 3 or more risk determinants is defined as metabolic syndrome [2]. On the other hand, insulin resistance, hyperglycemia, or known diabetes are central components of the World Health Organization definition [1]. Recently, the International Diabetes Federation released a consensus clinical definition for metabolic syndrome [5]. The International Diabetes Federation definition considers central obesity as the prerequisite, and it has broader criteria for waist circumference, HDL-C, and fasting plasma glucose [5].

Several studies suggest that metabolic syndrome starts early in life [6], [7], [8], [9], yet definition of metabolic syndrome in children and adolescents remains controversial [10]. Ethnic differences exist in the criteria, definition, and prevalence of metabolic syndrome in adolescents between populations [11], [12]. Understanding ethnic differences is crucial for the development of screening and treatment strategies. We examined a representative sample of apparently healthy students from Ankara, Turkey.

An increase in waist circumference is used to define central obesity in adults. Body proportions normally change during pubertal development and may vary among persons of different races and ethnic groups. Studies suggest that body mass index (BMI) may correlate better with blood pressure and dyslipidemia than does the waist circumference [13]. We therefore defined obesity based on age- and sex-specific cutoff points of BMI, which were developed and published from the centile curves of an international reference population [14]. Using the international cutoff points and percentiles, we determined children with high blood pressure, high TG, low HDL-C, fasting glucose of 100 mg/dL or greater, and elevated BMI corresponding to overweight or obesity. Because of the lack of standardization and unavailability of assays for insulin, we used the NCEP definition of metabolic syndrome.

The aims of this study were (a) to determine the prevalence of metabolic syndrome in Turkish students living in an urbanized and low to middle socioeconomic class environment in Ankara and (b) to determine the prevalence and importance of different risk factors of metabolic syndrome in Turkish students.