Overweight/obesity plays a central role in metabolic syndrome, a major health problem from infancy to adulthood (1). To identify and apply preventive and therapeutic measures at its earliest stages, the prevalence of its components were studied among a sample of high normal–weight, overweight, and obese Brazilian adolescents (2).
A total of 314 adolescents aged mean ± SD 13.8 ± 1.97 years were selected from two private and two public schools, of whom 178 (56.7%) were girls and 163 (51.9%) nonwhites. The approval of the university ethics committee and written informed consent were obtained. The students were divided into three BMI-based groups: high normal (≥50th and <85th percentile) 169 (53.8%) (2), overweight (≥85th and <95th percentile) 86 (27.4%), and obese (≥95th percentile) 59 (18.8%).
BMI (calculated as weight in kilograms divided by the square of height in meters), waist circumference, systolic and diastolic blood pressure, 12-h fasting total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and fasting glucose were measured using standard methods.
Diagnosis of metabolic syndrome was based on three of the following five criteria: HDL cholesterol <50 mg/dl (<45 mg/dl for boys aged 15–19 years), triglycerides ≥100 mg/dl, glucose ≥100 mg/dl, waist circumference >75th percentile for age and sex, and blood pressure >90th percentile for age, sex, and height (3).
Girls predominated within the high normal and overweight groups (61.0 and 59.3%, respectively, P = 0.0022) and boys within the obese group (59.3%, P = 0.022). Mean values for waist circumference, systolic blood pressure, diastolic blood pressure, glucose (P = 0.000 for all), and triglycerides (P = 0.020) increased in parallel to BMI increase, while HDL cholesterol decreased significantly (P = 0.000). The diagnosis of metabolic syndrome was made in 7.1% high normal, 27.9% overweight, and 59.3% obese individuals (30.9% males vs. 16.3% females, P = 0.002). No differences were found between private and public school students or among races. A low HDL cholesterol (94.4%) and increased waist circumference (90.1%) were the most frequently identified components of the metabolic syndrome, followed by elevated triglycerides (73.2%) and blood pressure (62.0%), with corresponding prevalence ratios (PRs) of 16.5 (95% CI 6.2–44.2), 12.3 (5.8–25.9), 6.5 (4.1–10.4), and 6.4 (4.3–9.4), respectively. High fasting glucose was the weakest marker for metabolic syndrome (PR 4.2 [95% CI 3.1–5.9]). In the cases of 12 individuals in the high normal group, a low HDL cholesterol (n = 12) and elevated triglycerides (n = 11) and blood pressure (n = 7) were the most frequent markers of metabolic syndrome found.
The 22.6% prevalence of the metabolic syndrome among these adolescents is high, reaching 59.3% in the obese group. Indeed, among children with BMI ≥85th percentile, the prevalence is even higher than that reported by de Ferranti et al. (3), whose diagnostic criteria were adopted in this study (40.7 vs. 31.2%, respectively). Furthermore, of particular note was detection of the syndrome among high normal adolescents. A low HDL cholesterol and increased waist circumference and triglycerides were the strongest markers for metabolic syndrome in the overweight and obese groups and low HDL cholesterol, high triglycerides, and elevated blood pressure in the high normal–weight group. The high prevalence of metabolic syndrome in these Brazilian adolescents is worrying, and early detection of each of these strong markers should prompt a thorough metabolic evaluation.
