Sex hormone-binding globulin levels and metabolic syndrome and its features in adolescents.

BACKGROUND: Low levels of sex hormone-binding globulin (SHBG) are associated with obesity, insulin resistance, and metabolic syndrome (MS) in men and women, and it has been suggested that SHBG could be a useful marker for MS risk. OBJECTIVE: The aim of this study was to analyze the relationship of SHBG levels with MS and its components in Spanish adolescents. METHODS: The sample population of this cross-sectional study was comprised of 386 male and 429 female adolescents, aged 12-16 yr. Anthropometric parameters and blood pressure (BP) were measured. Total cholesterol, high-density lipoprotein (HDL)-cholesterol, insulin, glucose, and SHBG levels were determined. The pediatric International Diabetes Federation (IDF) definition was used to classify adolescents for MS. RESULTS: SHBG levels were lower in adolescents with MS or with some MS features. More than 90% of the abdominally obese adolescents were in the lowest and medium SHBG tertiles. In girls, BP was significantly higher in the lowest SHBG tertile than in the two others, whereas in boys BP levels were significantly higher in the lowest and medium tertiles than in the highest one. Insulin levels and homeostasis model assessment (HOMA) index were also significantly higher in the lowest SHBG tertile than in the two others. CONCLUSIONS: The associations of SHBG with MS and its components, such as abdominal obesity, high BP or insulin levels, are already present in normal adolescents. This may suggest the possibility of using SHBG levels as a biomarker for MS risk in adolescents as well as adults.

Leptin and adiponectin levels in pubertal children: relationship with anthropometric variables and body composition.

BACKGROUND: Adipocytokines play an important role in controlling energy homeostasis, and in various metabolic processes related to obesity. The aim of this study was to describe serum leptin and adiponectin concentrations in a sample of pubertal Spanish children and to evaluate their association with anthropometric parameters and body composition. METHODS: The study included 833 pubertal boys and girls. Serum leptin and adiponectin concentrations were determined by ELISA. RESULTS: Leptin concentrations were significantly higher (p<0.0001) in obese or overweight (OW) children compared with children with normal weight (NW). Adiponectin was significantly lower (p<0.01) in obese or OW girls compared with girls of NW, although these findings were not the same for boys. Weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), and waist to hip ratio were significantly correlated (p<0.01) with leptin concentrations in both genders. Correlation of leptin with fat mass and % fat mass was strong, particularly in boys. The association of adiponectin concentrations with anthropometric variables was weaker in both genders. No significant correlations were found between adiponectin concentrations and fat mass or % fat mass. CONCLUSIONS: In summary, our study showed that, in pubertal children, leptin is related to weight, BMI, WC and HC and correlates even more strongly with % fat mass. However, adiponectin was weakly related to anthropometric variables and was not correlated with body fat.

Dehydroepiandrosterone sulfate (DHEA-S) distribution in Spanish prepuberal children: relationship with fasting plasma insulin concentrations and insulin resistance.

BACKGROUND: The aim of this study was to analyze dehydroepiandrosterone sulfate (DHEA-S) levels in a population-based sample of Spanish prepuberal children and to investigate the relationship between DHEA-S and insulin. METHODS: 854 (440 boys and 414 girls) randomly selected prepuberal children were included in our study after a sampling. Children were 6 to 8 years old and were classified for the analysis in half-year intervals. DHEA-S and insulin levels were measured. RESULTS: DHEA-S levels increase significantly with age during prepuberty reaching the maximum level of DHEA-S for this period at 7.5 years old in girls and 8 years old in boys. Girls have significantly higher log DHEA-S levels than boys, except at the age of 8, where the levels are similar (median: 41.7 nmol/l girls and 41.1 nmol/l boys). DHEA-S correlates positively and significantly with weight, height, and BMI in all age intervals but the correlation between DHEA-S and insulin and HOMA is present only at the age of 6.5 in boys and 8 in girls. CONCLUSIONS: We report data about the distribution of DHEA-S in the Spanish prepuberal population. The maximum level of DHEA-S in this prepuberal period was reached before in girls than in boys, with girls having higher DHEA-S levels than boys until the end of this period. We found an important association between DHEA-S levels and weight, height and BMI but an inconsistent association of DHEA-S with insulin and HOMA.

Insulin and HOMA in Spanish prepubertal children: relationship with lipid profile.

OBJECTIVE: The effects of insulin or insulin resistance on the lipid profile seem to change with age. The aim of this study was to analyze insulin levels and an insulin resistance index and to investigate the relationship between these and the lipid profile in a population-based sample of Spanish prepubertal children. METHODS: 1048 (524 boys and 524 girls) randomly selected prepubertal children were studied. Children were 6 to 8 years old with a mean age of 6.7. Plasma lipid, FFA and insulin levels were measured. The homeostatic model assessment (HOMA) was calculated as an indicator of insulin resistance. RESULTS: When analyzing percentile values of insulin, HOMA and FFA by sex, we observed that girls had significantly higher insulin concentrations than boys (except at the 10th percentile) and significantly higher FFA (except at the 90th percentile) with no significant differences between sexes for HOMA. Multivariate regression analyses showed that insulin was positively associated with glucose, triglycerides and apoB in boys but not in girls, and negatively associated with FFA in both genders. CONCLUSIONS: We report here data about the distribution of insulin in the Spanish prepubertal population. The higher levels of insulin in prepubertal girls could indicate that girls start to be more insulin resistant than boys at this age, although other manifestations of insulin resistance are not yet detectable.

Genetic determinants of plasma HDL-cholesterol levels in prepubertal children.

INTRODUCTION: Genetic determinants have been related to variation of high-density lipoprotein cholesterol (HDL-C) levels, but the extension of this association remains controversial. In our study, we analyzed the contribution of several polymorphisms on HDL-C-related genes to variation of plasma HDL-C in prepubertal children. METHODS: We studied 1269 (641 males and 628 females) 6-8 years old healthy children, who participated in a cross-sectional study examining cardiovascular risk factors in Spain. Common genetic variants in the apolipoprotein AI, apolipoprotein AII, cholesteryl ester transfer protein (CETP), hepatic lipase, ATP-binding cassette transporter A1, and paraoxonase genes were determined by PCR. RESULTS: CETP TaqI B2 carrier girls had significantly higher HDL-C levels than B1B1 girls. B2B2 boys had significantly higher (p<0.001) HDL-C than B1B1and B1B2 boys. In linear regression analysis, CETP TaqIB appears as the main predictor of HDL-C plasma levels, accounting for 4.5% and 1.8% of HDL-C variation in girls and boys respectively. CONCLUSIONS: Our data showed that among the studied polymorphisms only the CETP TaqIB polymorphism contributes to the variation in HDL-C levels in prepubertal children, particularly in girls, but overall these polymorphisms explain a small part of the variation of HDL-C plasma levels at this age.

Hormone levels in 12- to 15-year-old boys and girls in Spain and their relationship with anthropometric variables.

OBJECTIVE: To determine hormone levels in a population-based sample of pubertal children and evaluate their association with anthropometric parameters. METHODS: Sex steroid levels were assessed using RIA and IRMA. RESULTS: In boys, changes in weight and height across the period were accompanied by changes in testosterone and SHBG. In girls, anthropometric variables did not change and were not correlated with estradiol. CONCLUSIONS: We observed an association between hormone levels and anthropometric changes when active growth associated with puberty was taking place.

Dehydroepiandrosterone sulfate and high-density lipoprotein-cholesterol levels in overweight children.

OBJECTIVE: The association of childhood overweight with cardiovascular risk factors seems to change by sex and age, which may indicate that hormonal status could be the cause of this different association. In this study, we analyzed the relationship of dehydroepiandrosterone sulfate (DHEA-S) with the alterations associated with overweight by analyzing the influence of this hormone in the differences found in biochemical variables between normal-weight and overweight prepubertal children. RESEARCH METHODS AND DESIGN: The study included 684 6- to 8-year-old children (350 boys and 334 girls) categorized by the presence or absence of overweight, according to the age- and sex-specific cut-off points proposed for children. Lipid levels were determined by standard methods. DHEA-S and insulin levels were measured by radioimmunoassay. Biochemical variables were compared between normal-weight and overweight children by tertiles of DHEA-S. RESULTS: We observed that plasma high-density lipoprotein-cholesterol (HDL-C) and apolipoprotein (apo)-AI levels were significantly lower in overweight than in normal-weight boys only in the highest tertile of DHEA-S. No significant differences in plasma glucose levels, total cholesterol, low-density lipoprotein-cholesterol, or apo B were found between overweight and normal-weight children in any DHEA-S tertile. In a Spearman correlation analysis, we observed a significant and negative correlation for weight and BMI with HDL-C and for weight and apo-AI levels only in the highest tertile of DHEA-S. DISCUSSION: Our study showed that, in our prepubertal population, the association of overweight with decreased HDL-C and apo-AI levels was present only in boys within the highest levels of DHEA-S, supporting the importance of hormonal influences on the association of metabolic alterations with overweight.