Serum leptin concentrations in relation to pubertal development

OBJECTIVES: The amount of adipose tissue influences pubertal development and fertility in girls. A candidate for mediating this is the hormone leptin, derived from adipocytes. This work was carried out to determine whether the leptin concentration in serum is regulated during pubertal development. SUBJECTS AND METHODS: Serum concentrations of leptin were determined by radioimmunoassay in a sample of 252 healthy children representing all pubertal stages. RESULTS: Serum leptin concentrations correlated directly with age (r = 0.53), body mass index (BMI) (r = 0.71), and weight for height SD score (r = 0.44) in girls and with BMI (r = 0.33) and weight for height SD score in boys (r = 0.36). Leptin concentrations increased with pubertal development in girls, resulting in significantly higher concentrations at pubertal stages 4 and 5 than at the prepubertal stage, whereas there was no change in the boys. CONCLUSIONS: Serum leptin concentrations increased during pubertal development in the girls, but remained constant in the boys. Whether the increase in serum leptin concentrations in girls is of importance for, or a consequence of, pubertal development is still to be determined.     

No evidence for leptin as an independent associate of blood pressure in childhood and juvenile obesity

We studied whether leptin is an independent associate of blood pressure in obese children and adolescence. 102 obese children (48 girls, age: 11.6 +/- 2.22 yr; body mass index [BMI]: 27.45 +/- 4.4; blood pressure: 122.5 +/- 11.1/64.7 +/- 10.6 mm Hg and 54 boys, age: 11.5 +/- 2.4 yr; BMI: 27.6 +/- 4.4; blood pressure: 122.5 +/- 13.2/60.9 +/- 8.1 mm Hg [mean +/- SD]) were investigated. Serum leptin and insulin were measured by RIA; glucose was determined enzymatically. Fat mass (FM) was calculated by bioelectrical impedance. Leptin was higher in girls than in boys (p=0.018) but no significant gender differences were found with respect to indices of adiposity and systolic blood pressure (SBP). Children were divided into three groups, according to pubertal stage (Group 1: prepubertal, 32 boys/13 girls; Group 2: pubertal, 17 boys/25 girls; Group 3: late/postpubertal, 5 boys/10 girls). SBP and DBP correlated with body weight in the whole group (r=0.49, p<0.0001, and r=0.27, p=0.004). In Group 1, BMI showed the highest correlation to SBP; in Group 3 no indices of adiposity were related to SBP. In no case was leptin significantly associated with SBP after adjustment for adiposity. In Group 2, glucose was significantly associated with SBP after adjustment for body weight. In Group 3, however, no correlations were found between SBP, DBP and metabolic characteristics, perhaps due to small sample size. Stepwise multiple regression revealed that body weight and glucose contributed to the variation in SBP in the whole group (R2=0.31, p<0.0001). Insulin accounted for almost 8% of the variation in DBP (R2=0.08, p=0.0034). Body weight contributed significantly to SBP in boys (R2=0.39, p<0.0001) and girls (R2=0.24, p< 0.001). The results imply that body weight contributes independently to the variation in blood pressure. Glucose and insulin contribute to mean blood pressure to some extent, but our data do not support the assumption that leptin per se serves as an independent predictor of blood pressure in obese children and adolescents.     

No relationship between leptin and cortisol in obese children and adolescents

Recent findings have shown that leptin downregulates the steroid producing system in the adrenal. We studied the interactions of leptin, insulin and cortisol in obese children and adolescents at different stages of maturation. In 44 boys (age 11+/-3.1 yr, body mass index [BMI] 29+/-5.3 [mean +/- SD]) and 35 girls (age 11.4+/-2.6 yr, BMI 29+/-4.3), blood levels of leptin, insulin, cortisol, and glucose were determined. Fat mass (FM) was calculated by bioelectrical impedance. No significant differences were found between boys and girls with respect to humoral and anthropometric characteristics. When children were divided according to maturation stage (prepubertal, pubertal, and late/postpubertal) insulin was higher in the more mature groups (p<0.01) and leptin was higher in the pubertal group (p=0.03). In the prepubertal and pubertal groups, the expected positive relationship between adiposity and leptin was found although the magnitude of this association decreased with maturity. In none of the groups studied was cortisol significantly correlated to leptin. Insulin (p=0.03) and glucose (p=0.01) were positively associated with cortisol in the prepubertal group after adjustment for adiposity. However, in the pubertal group an inverse correlation was found between insulin and cortisol (p=0.03), and between insulin and glucose after control for adiposity. In the late/ postpubertal group, no significant correlations were found between estimates of adiposity and humoral parameters even after adjustment for gender. Stepwise multiple regression failed to detect a significant influence of cortisol to explain the variation in leptin, and vice versa. BMI contributed to the variation in leptin (adj. R2 =0.275, p<0.0001), and glucose added 5% to the variation in cortisol (p=0.03). The results do not confirm the inverse association between leptin and cortisol found in adults. Although BMI reflects levels of leptin, it is likely that several other factors in conjunction with fatness modulate the relationship with leptin. Whether leptin per se exerts an influence on the hypothalamic-adrenal-adipo axis remains to be investigated in longitudinal studies.     

Relationships of IGF-I and andrrogens to skeletal maturation in obese children and adolescents

IGF-I and androgens are postulated to accelerate skeletal maturation in obese children. METHODS: We studied weight status (BMI-SDS), height-SDS, IGF-I, cortisol, DHEA-S, and testosterone in 356 obese children (aged 4-15 years; 54% females) and correlated them to differences between bone age and chronological age (deltaBA-CA). Direct multivariate linear regression analyses were conducted for the dependent variable deltaBA-CA, including BMI, age, gender, pubertal stage, IGF-I-SDS, cortisol, DHEA-S, and testosterone as independent variables separately in prepubertal and pubertal girls, and prepubertal and pubertal boys. RESULTS: Height-SDS (r = 0.52), IGF-I (r = 0.33), and IGF-I-SDS (r = 0.36) were significantly (p < 0.001) correlated to deltaBA-CA. In multiple regression analyses, BMI and IGF-I-SDS were significantly positively (p < 0.001) correlated to deltaBA-CA independently of gender and pubertal stage. Testosterone was significantly positively correlated to detaBA-CA only in prepubertal girls (p = 0.035). CONCLUSIONS: Since IGF-I concentrations were positively associated to deltaBA-CA independently of pubertal stage and gender, we put forward the hypothesis that this hormone may contribute to acceleration of skeletal maturation in obese children.     

Changes in leptin, insulin and body composition in obese children during a weight reduction program

BACKGROUND: Girls have higher leptin concentrations than boys at all stages of biological development and this is also seen in the state of obesity. Little is known about whether gender and biological development of obese children influence changes in leptin associated with a short-term weight reduction program. OBJECTIVE: To study whether leptin concentration, body composition and insulin levels in obese children were influenced by a 3-week intervention program including diet and sports. STUDY DESIGN: Sixty-two obese children (32 boys and 30 girls) were examined before and after the intervention program. Body composition was measured by bioelectrical impedance and BMI-SDS was calculated. Serum leptin and serum insulin were determined by RIA. RESULTS: Girls had higher leptin levels than boys, before and after the weight reduction program. Body mass, fat mass (FM), leptin and insulin were decreased after the intervention in both sexes. We found a greater change in serum leptin in girls but the change in FM was of greater magnitude in boys. However, percentage changes in leptin were not significantly different between the sexes. Before the intervention, leptin concentrations were correlated with %FM, FM and moderately with BMI-SDS in all children. Only in pubertal boys did correlation of leptin with %FM increase after the intervention (from r=0.57 to r=0.75, p<0.01). Changes in leptin were found to be associated with initial leptin values in boys (r=0.95, p<0.01) and in girls (r=0.93, p<0.01), independent of Tanner stages. CONCLUSION: Serum leptin levels were positively correlated with adiposity in obese children and a diet and sports intervention program decreased serum leptin, insulin and body fat in all children. Changes in leptin were best described by the initial leptin concentration. The increase in correlation of leptin with %FM in obese pubertal boys after the intervention could have its underlying mechanism in an increased sensitivity to leptin and anabolic hormones.     

Relationship between fat distribution and lipid and apolipoprotein profiles in young teenagers

The influence of obesity and fat distribution on serum levels of lipoprotein and apolipoprotein was investigated in 294 Japanese junior high school children (12-13 years of age). Serum levels of low-density lipoprotein cholesterol (LDLC) (P= 0.013), triglycerides (TG) (P= 0.0006), and apolipoprotein B (apoB) (P= 0.003), and the apoB/A-I ratio (P= 0.005) were significantly higher and serum levels of high-density lipoprotein cholesterol (HDLC) (P= 0.00003) and apoA-1(P = 0.003) were significantly lower in obese boys than in non-obese boys. The serum levels of TG (P = 0.013) and the apoB/A-1 ratio (P= 0.011) were significantly higher and the serum levels of HDLC (P= 0.004) was significantly lower in obese girls than in non-obese girls. The LDLC/apoB ratio was lower in obese girls than in non-obese girls (P= 0.03). Obesity ( 20% of ideal weight) was strongly correlated with the serum levels of lipids and apolipoproteins in boys; this relationship was less clear in girls. The degree of obesity and the body mass index (BMI) were more strongly correlated with serum levels of lipids and apolipoproteins in boys than in girls. In boys, atherogenic-lipoproteins and apolipoproteins, such as LDLC and apoB, showed a stronger correlation with the thickness of the triceps skinfold, while in girls the anti-atherogenic lipoproteins and apolipoproteins, such as HDLC and apoA-1, showed a stronger correlation with both the triceps and the subscapular skinfold thicknesses. In girls the relationships between the BMI and the degree of obesity and the thickness of the subscapular skinfold (S) thickness were similar to the relationships between those parameters and the triceps skinfold (T) thickness. In boys, these parameters showed a stronger correlation with the subscapular skinfold thickness than with the triceps skinfold thickness. The correlation coefficients for the relationships between skinfold thickness and lipid and apolipoprotein levels were similar to the coefficients for the relationships between skinfold thicknesses and the severity of obesity and the BMI. The distribution of central-type fat accumulation, which is indicated by the thickness of the subscapular skinfold, the S/T ratio and S-T value, was inversely correlated with the HDLC level in both boys and girls. The degree of obesity was strongly correlated with the atherogenic lipoprotein profile in boys, in part because the subscapular skinfold thickness was strongly correlated with the degree of obesity and the BMI. In girls, the correlations between indices of central-type obesity and atherogenic lipid and apolipoprotein profiles were stronger than in boys. These data suggest that childhood obesity may be an early cardiovascular risk factor.     

The relationship between different subcutaneous adipose tissue layers, fat mass and leptin in obese children and adolescents

We studied the relationships of subcutaneous adipose tissue layers (SAT-layers), body fat mass (FM) and waist-to-hip ratio (WHR) with leptin in obese children and adolescents. Twenty-nine obese children and adolescents (12 boys: age: 11.3 +/- 3.7 yr; body mass index [BMI]: 28.5 +/- 4) and 17 girls (age: 12.2 +/- 2.2 yr; BMI: 29.8 +/- 4.7) (mean +/- SD) were studied. FM was estimated by bioelectrical impedance. SAT-layers were determined at 15 different body sites from 1-neck to 15-calf by the Lipometer optical device. Leptin and insulin were determined by RIA. Maturity was associated with a greater thickness of certain SAT-layers from the upper body and with a lower thickness of SAT-layers from the abdominal region and lower extremities. Significant correlations were found for all estimates of adiposity and leptin (all p<0.001). Waist and hip circumferences were not correlated to leptin after adjustment for FM. SAT-layers from the upper body were significantly and positively correlated to leptin. Multiple regression analysis revealed FM as a main contributor to the variation in leptin (R2=0.53, p<0.0001). FM together with SAT-layers 5-front chest and 13-rear thigh explained 72% of the variation in leptin (p<0.0001). In a body fat distribution model, hip circumference together with SAT-layers 4-upper back and 2-triceps explained 75% of the variation in leptin (p< 0.0001). The results suggest that SAT-layers and their topography are main determinants for leptin in obese children and adolescents. Maturity in obese children is associated with higher values of upper body SAT-layers and lower values of abdominal and lower extremities SAT-layers. Whether leptin is under the control of certain subcutaneous adipose tissue depots from the upper body remains to be elucidated by longitudinal studies.     

Insulin and insulin resistance index are not independent determinants for the variation in leptin in obese children and adolescents

Recent findings have questioned the independent influence of insulin on leptin. We studied whether insulin contributes to leptin in obese children, independent of confounding parameters, such as total adiposity, fasting insulin resistance index, and fat free mass. In 100 obese boys and 103 obese girls, blood levels of leptin, insulin, glucose, and triglycerides were determined. The fasting insulin resistance index (FIRI) was calculated, and body composition was assessed by means of impedance. Leptin and glucose were higher in girls, and all estimates of adiposity were significantly associated with leptin. However, when adjusted for adiposity, the relationship between insulin and leptin, and also between FIRI and leptin, remained significant in boys and girls (p<0.05). Although several regression models were tested, neither insulin nor FIRI were found to contribute significantly and independently to leptin. BMI together with triglycerides and FFM were the main determinants for the variation in leptin in boys (adj. R2=0.46, p<0.0001). In girls, BMI explained a great magnitude of the variation in leptin (adj. R2=0.60, p<0.0001). These findings indicate that in the state of childhood and adolescent obesity, total adiposity but not insulin or insulin resistance index is the main determinant for leptin. In contrast to obese girls, the fat free mass and triglycerides contribute significantly to the variation in leptin in obese boys. The biological significance for these findings should be elucidated in longitudinal studies.     

Relation of serum leptin and insulin-like growth factor-1 levels to intima-media thickness and functions of common carotid artery in children and adolescents with type 1 diabetes

BACKGROUND AND AIM: Leptin and insulin-like growth factor-1 (IGF-1) have been suggested to be involved in the pathogenesis of atherosclerosis. The aim of this study was to evaluate the relationship between serum leptin, IGF-1 and intima-media thickness (IMT) and functions of common carotid artery (CCA) in children and adolescent patients with type 1 diabetes. MATERIAL AND METHODS: Serum leptin and IGF-1 levels were measured in 45 diabetic patients (23 girls and 22 boys). Age, diabetes duration as well as major cardiovascular risk factors, including anthropometric and metabolic parameters, were matched between girls and boys. The relation of serum leptin and IGF-1 levels to CCA structure and functions were measured by ultrasonography as IMT, cross-sectional compliance (CSC), cross-sectional distensibility (CSD), diastolic wall stress (DWS) and incremental elastic modulus (IEM). RESULTS: Serum leptin levels of diabetic girls were higher than those in the boys (21.8 +/- 14.5 microg/l vs 8.9 +/- 10.6 micro/l, p = 0.002). However, the difference for serum IGF-I levels was not significant between diabetic girls and boys (240.7 +/- 96.8 ng/ml vs 234.7 +/- 93.2 ng/ml; p > 0.05). In all subjects, leptin levels were correlated with CSC (p = 0.04), CSD (p = 0.04) and IEM (p = 0.01), and IGF-1 levels were only correlated with CSC (p = 0.01). Leptin did not show any correlation with ultrasonographic measurements in both girls and boys separately. IGF-1 was correlated with CSC (p = 0.001), CSD (p = 0.002) and IEM (p < 0.001) in boys but not in girls. In a multivariate regression model, IGF-1 emerged as independent correlates for mean CSD and IEM in boys but not in girls. CONCLUSION: Serum leptin and IGF-1 levels in children and adolescent patients with type 1 diabetes are associated with functions of common carotid artery, and the association of IGF-1 levels is influenced by sex.     

Leptin levels in boys with pubertal gynecomastia

BACKGROUND: It has been reported that there is a relationship between circulating leptin and sex steroid hormones and leptin is able to stimulate estrogen secretion by increasing aromatase activity in adipose stromal cells and breast tissue. Leptin receptors have been also shown in mammary epithelial cells and it has been suggested that leptin is involved in the control of the proliferation of both normal and malignant breast cells. AIM: To investigate circulating leptin levels in boys with pubertal gynecomastia. METHODS: Twenty boys with pubertal gynecomastia who were in early puberty and had no obesity, and 20 healthy individuals matched for age, pubertal stage and body mass index (BMI) with the study group, were enrolled in the study. Body weight, height and left midarm circumference (MAC) and left arm triceps skinfold thickness (TSF) were measured and BMI was calculated. A fasting blood sample was collected and routine hormonal parameters including prolactin, beta-human chorionic gonadotropin (betaHCG), total and free testosterone, estradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, androstenedione (AS) and dehydroepiandrosterone sulfate (DHEAS) levels were studied. Serum leptin levels were analyzed using radioimmunoassay. RESULTS: The mean ages of the study and control group were not different (13.9 +/- 0.89 and 14.2 +/- 0.66, respectively). No significant difference was found for BMI, MAC and TSF values between the two groups. There was no significant difference for hormonal parameters including FSH, LH, total and free testosterone, estradiol, AS, DHEAS and estradiol/total testosterone ratio between boys with pubertal gynecomastia and the controls. Serum leptin levels were found significantly higher in the study group compared with the healthy controls (5.58 +/- 0.81 and 2.39 +/- 0.29 ng/ml, respectively; p <0.001). No correlation could be determined between serum leptin levels and hormonal parameters. CONCLUSION: The presence of higher leptin levels in boys with pubertal gynecomastia indicates that leptin may be involved in the pathogenesis of pubertal gynecomastia. The role of circulating leptin in pubertal gynecomastia is probably related to increase in estrogen and/or estrogen/ androgen ratio by the stimulating effect of leptin on aromatase enzyme activity in both adipose and breast tissues, or a direct growth stimulating effect of leptin on mammary epithelial cells, or increase in sensitivity of breast epithelial cells to estrogen with inducing functional activation of estrogen receptors by leptin in breast tissue.     

新疆伊犁地区2438例哈萨克族儿童血压现况分析

目的：了解新疆伊犁地区哈萨克族儿童血压水平和高血压的发生状况及影响因素。方法：2009年5~6月采用随机整群抽样方法,抽取新疆伊犁地区哈萨克族学龄儿童2438例,进行身高、体重、腰围、臀围、皮褶厚度、血压测量,并计算体质指数（BMI）。结果：2438名儿童收缩压（SBP）平均水平为94±13 mm Hg,舒张压（DBP）平均水平为60±9 mm Hg,低于国内同年龄段汉族平均水平;检出高血压儿童138名,患病率5.66%（138/2438）,其中男童患病率4.38% （54/1232）,女童患病率6.97%（84/1206）,女童患病率高于男童（P<0.05）;血压及高血压患病率与BMI、腰围、臀围、皮褶厚度、性别、年龄均呈正相关。结论新疆伊犁地区哈萨克族儿童血压平均水平较国内儿童低;女童高血压患病率高于男童;肥胖与哈萨克族儿童高血压患病率密切相关。     

The interaction of obesity and puberty on substrate utilization during exercise: a gender comparison

The study evaluated the interactions of puberty and obesity on substrate oxidation of overweight girls (n = 38) and boys (N = 35; BMI > 85th percentile) matched for gender, age, and puberty (pre/pubertal) with normal weight girls and boys. Metabolic rates (VO(2)) were obtained during rest and at 4, 5.6 and 8 k/h. Carbohydrate oxidation rates (mg/kgFFM/min) adjusted for % predicted VO(2max), were higher for prepubertal OW children than pubertal children (p < .03). Fat oxidation rates were higher for NW prepubertal boys compared with other boys. Results indicate that OW children, regardless of gender or pubertal status, increase their carbohydrate oxidation rate to compensate for higher than normal metabolic rates. The effects of obesity on the substrate use is marginally related to puberty.     

Body fatness and serum lipids of 11-year-old Chinese children

It has been suggested that distribution of body fat has a stronger bearing on health risk than total body fat. Magnetic resonance imaging (MRI) was used to examine the distribution of fat and correlated with body fat assessed by the usual clinical methods-weight, weight-for-height, body mass index (BMI), triceps and subscapular skinfold thickness in 11-y-old Chinese children. Lipid profiles were used as indicators for coronary risk. Eighty-eight subjects had body fat distribution estimated by MRI, while 49 had serum lipids measured. Anthropometric parameters correlated significantly with total fat at the umbilical level measured by MRI (weight: r = 0.90 in boys, 0.75 in girls; BMI: r = 0.94 in boys, 0.87 in girls; percent median weight-for-height: r = 0.90 in boys, 0.79 in girls, triceps skinfold thickness: r = 0.89 in boys, 0.90 in girls; subscapular skinfold thickness: r = 0.93 in boys, 0.88 in girls). Obese subjects had proportionally less visceral fat than subcutaneous fat at umbilical level. Using stepwise multiple regression, predictive factors for high-density lipoprotein cholesterol were BMI in boys and breast-staging in girls. For triglycerides, it was genital staging in boys and for total cholesterol, it was breast-staging in girls. Visceral fat was not a significant determinant of serum lipids.     

Leptin is closely related to body fat in prepubertal children aged 8-11 years

BACKGROUND: In adults and obese children, serum leptin concentrations are closely related to body fat. AIM: To investigate whether such a relationship between leptin concentrations and body fat is also evident in children with a relatively normal body composition. METHODS: The study was a cross-sectional population study in 170 Caucasian children (91 boys and 79 girls), with a mean age of 9.9+/-0.6 y (range 8.5-10.9 y) and a mean BMI of 17.4+/-2.6 (range 12.8-28.1). Serum leptin was measured and compared to total body fat as determined by dual-energy X-ray absorptiometry. RESULTS: In the whole population, serum leptin concentrations were highly correlated with total body fat (r=0.83, p<0.001). A stepwise forward multi-regression analysis revealed that the inclusion of other anthropometrical data did not add any significance to the model. Leptin concentrations were significantly higher in girls (5.2 ng/ml) than in boys (3.2 mg/ml; p=0.003). Gender differences still prevailed (p=0.007) after adjusting for number of kilograms of fat tissue. CONCLUSION: This study shows that, already at the young age of 9-11 y, an adult-like pattern of regulation of leptin exists. This indicates similar risk factor dependency of leptin across all age groups.     

Leptin, insulin-like growth factor (IGF)-I and IGF binding protein-3 levels in children with constitutional delay of growth

This study was planned in order to investigate the role of insulin-like growth factor-I (IGF-I), IGF binding protein-3 (IGFBP-3) and leptin, the product of the ob gene synthesized by fat tissue cells, in constitutional delay of growth and puberty (CDGP) which is the most frequent cause of short stature in children. This study was conducted on 80 children with CDGP aged 6-15 years, and 60 healthy children served as controls. Serum IGF-I, IGFBP-3, insulin and plasma leptin levels were measured by immunoradiometric assay. Mean IGF-I and leptin levels were significantly lower in the CDGP group compared with the controls, but the mean IGFBP-3 level was not different in the two groups. Mean leptin levels were 3.72 +/- 2.29 in CDGP and 4.68 +/- 3.08 in the control group (p <0.05). There was a statistically significant relationship between leptin levels and height, weight, and body mass index. Leptin levels were also correlated with chronological age, bone age and height age. When evaluated according to pubertal status, a significant difference was found in IGF-I, leptin and IGFBP-3 levels between prepubertal and pubertal groups. Leptin levels were significantly different in the prepubertal CDGP group compared with controls but in the pubertal CDGP group only IGF-I levels were significantly different from controls. As the weight of children with CDGP was lower than in the control group, it is postulated that the reason for short stature and pubertal delay may be this decrease in weight which is also the cause of low levels of leptin and IGF-I.     

瘦素和脂联素在儿童肥胖相关性高血压发病中的作用

目的探讨瘦素和脂联素在儿童肥胖相关性高血压发病中的作用。方法基于北京市儿童青少年代谢综合征研究项目的现况调查结果，非随机选择3 502名6~18岁学龄儿童（其中男1 784名，女1 718名）为研究对象，按照超重（包括肥胖）和高血压状态将研究对象分为4组，正常体重正常血压组（对照组，1 497名）、正常体重高血压组（HBP组，125名）、超重但血压正常组（OB组，1 349名）和超重合并高血压组（OB+HBP组，531名）。通过比较4组人群血清瘦素和脂联素水平，以及瘦素和脂联素与血压之间的相关回归分析，探讨其与肥胖和血压之间的关系。结果超重肥胖人群BMI、血压、胰岛素和瘦素水平显著升高，脂联素水平降低。HBP组与对照组BMI、瘦素、脂联素水平差异无统计学意义。OB组和OB+HBP组与对照组比较，BMI、SBP、DBP、胰岛素和瘦素水平升高，脂联素水平降低，与HBP组比较仍可见BMI、胰岛素和瘦素水平升高，脂联素水平降低。与OB组比较，OB+HBP组BMI和胰岛素水平及男性的瘦素水平明显升高。血压与年龄、BMI、胰岛素、瘦素均呈显著正相关（r=0.260~0.643,P<0.01），与脂联素呈显著负相关（r=-0.171~-0.332, P<0.01）。但在调整胰岛素或BMI后，瘦素、脂联素与血压的相关性减弱或消失。结论 超重人群血压、胰岛素及瘦素水平均高于对照人群，脂联素水平低于对照人群。瘦素、脂联素可能通过肥胖或胰岛素抵抗与血压相关。     

Serum leptin levels in obese Indian children relation to clinical and biochemical parameters

OBJECTIVE: To evaluate serum leptin levels in obese Indian children and its correlation to anthropometric and biochemical parameters. DESIGN: Cohort study. SETTING: Referral tertiary hospital. METHODOLOGY: Leptin levels were measured in 36 children (26 boys, age 1.5 to 15 years) and 37 adults (21 men, age 25 to 69 years) with obesity and 29 normal weight controls (15 children and 14 adults). RESULTS: Leptin levels were higher than controls in obese children (19.4 +/- 6.4 ng/mL against 5.4 +/- 1.7 ng/mL, p = 0.0001) and obese adults (18.9 +/- 6.4 ng/mL against 7.8 +/- 5.6 ng/mL, p = 0.0001). Leptin levels were higher than males in obese girls (23.5 +/- 1.7 ng/mL against 18.0 +/-7.6 ng/mL, p = 0.040) and women (21.3 +/- 4.4 ng/mL against 15.8 +/- 7.4 ng/mL). Leptin levels correlated with body mass index, waist circumference and waist to-hip ratio. A positive correlation was observed between serum leptin and cholesterol, triglycerides and LDL-cholesterol. No correlation was seen with fasting blood glucose and HDL-cholesterol. CONCLUSIONS: Leptin levels correlate significantly with anthropometric and laboratory parameters in obese children. There is a need for further studies on the role of leptin in childhood obesity and metabolic syndrome.     

Sex‐specific association between leptin receptor polymorphisms and leptin levels and BMI in healthy adolescents*

Aim: To examine the relationship of three common polymorphisms in the leptin receptor (LEPR) gene, implicated in the regulation of body weight, with leptin levels and obesity‐related phenotypes in a population‐based sample of healthy pubertal children in Spain. Methods: The study included 806 boys and girls aged 12–16 whose anthropometrical data and body composition were recorded. Serum leptin levels were determined by ELISA. The LEPR Q223R, K109R and K656N polymorphisms were determined by TaqMan® allelic discrimination assays. Results: When analysing the Q223R polymorphism, we observed that female carriers of the RR genotype had significantly higher plasma leptin levels (18.2 vs. 15.1 ng/mL p = 0.016) and significantly higher mean BMI values (22.5 vs. 21.3 Kg/m² p = 0.032) than QR carriers. Furthermore, the frequency of the RR genotype in overweight‐obese girls was significantly higher than that found in normal‐weight girls. No significant differences were observed in boys. Neither boys nor girls showed significant differences when comparing leptin levels, anthropometric variables or body composition by K109R or K656N genotype. Conclusion: The fact, that the Q223R polymorphism in the LEPR gene is significantly associated with leptin levels and BMI only in girls, suggests a sex‐specific influence of this polymorphism on these variables.     

Correlations between high level sport-climbing and the development of adolescents

Over the last years concerns have been raised about the health effects particularly on young climbers due to the observation of short stature with low body weight and body fat in sports climbers. The aim of this study was to investigate anthropometric and hormonal data for climbers of the German Junior national team. 16 climbers were compared with 14-age matched nonclimbers with respect to several anthropometric variables, leptin level, and climbing characteristics. Height, weight and body mass index (BMI) standard deviation scores (SDS) for boys were not significantly different from the controls, whereas girls had significantly lower SDS-values for weight and BMI. In comparison with the control group boys and girls had a lower skinfold thickness. The leptin values were lower than the calculated leptin levels but only reached significance for the girls. The young athletes of the GJNT were neither of short stature nor thin when compared with a physically active control group. The low body fat in boys and girls was within expected limits. The lower leptin levels might be attributed to a decrease in total body fat.     

Leptin and soluble leptin receptor levels in obese children in fasting and satiety states

AIM: To investigate the role of soluble leptin receptors in leptin resistance in obese children. METHODS: Thirty-one obese children (16 boys and 15 girls) with a median age of 12.1 years and 15 age- and sex-matched controls were included in the study. Leptin and soluble leptin receptor levels were measured in fasting and satiety states. RESULTS: Serum leptin levels were significantly higher and soluble leptin receptor levels were significantly lower in obese children compared to controls in fasting and satiety states. In obese children, there was a high and inverse correlation between leptin levels and soluble leptin receptor levels after fasting. Prepubertal obese children had lower leptin and higher soluble leptin, receptor levels compared to pubertal children in both states. CONCLUSION: In this study, being the first to consider both fasting and satiety states, obese children were found to have higher leptin, but lower soluble leptin receptor levels, compared to controls. With these findings, it can be postulated that leptin resistance in obese children originates from a defect of soluble leptin receptor production.