Nihal Hatipoglu

Insulin Resistance in Obese Children and Adolescents: HOMA-IR Cut-Off Levels in the Prepubertal and Pubertal Periods

Objective: Childhood obesity is associated with an increased risk for insulin resistance. The underlying mechanism for the physiological increase in insulin levels in puberty is not clearly understood. The aim of the present study was to determine the cut−off values for homeostasis model assessment for insulin resistance (HOMA−IR) in obese children and adolescents according to gender and pubertal status. Methods: Two hundred and eight obese children and adolescents (141 girls, 127 boys) aged between 5 and 18 years were included in the study. The children were divided into prepubertal and pubertal groups. A standard oral glucose tolerance test (OGTT) was carried out in all children. A total insulin level exceeding 300 μU/mL in the blood samples, collected during the test period, was taken as the insulin resistance criterion. Cut−off values for HOMA−IR were calculated by receiver operating characteristic (ROC) analysis. Results: In the prepubertal period, the rate of insulin resistance was found to be 37% in boys and 27.8% in girls,while in the pubertal period, this rate was 61.7% in boys and 66.7% in girls. HOMA−IR cut−off values for insulin resistance in the prepubertal period were calculated to be 2.67 (sensitivity 88.2%, specificity 65.5%) in boys and 2.22 (sensitivity 100%, specificity 42.3%) in girls, and in the pubertal period, they were 5.22 (sensitivity 56%, specificity 93.3%) in boys and 3.82 (sensitivity 77.1%, specificity 71.4%) in girls. Conclusions: Since gender, obesity and pubertal status are factors affecting insulin resistance, cut−off values which depend on gender and pubertal status, should be used in evaluation of insulin resistance. Conflict of interest:None declared.

Protein oxidation in obesity and insulin resistance

IntroductionAdvanced oxidation protein products (AOPP) are considered reliable markers to estimate the degree of oxidant-mediated protein damage. Data on oxidative stress in childhood obesity and insulin resistance are limited.ObjectiveThe aim of this study was to investigate the AOPP level as an oxidative stress marker in obesity and insulin resistance. The study included 57 pubertal obese children and adolescents (30 girls and 27 boys) and 20 healthy pubertal children and adolescents (11 girls and 9 boys). Materials and MethodsAll participants in the obesity group underwent an oral glucose tolerance test (OGTT) and two separate groups were formed according to the existence of insulin resistance. ResultsAOPP levels were measured in the obesity and control groups spectrophotometrically. The obesity group consisted of 25 children and adolescents with insulin resistance and 32 subjects without insulin resistance. AOPP levels in the obesity group were found to be significantly higher than those in the control group. Although AOPP levels in the subjects with insulin resistance were higher than the subjects without insulin resistance, there was no significant difference between AOPP levels of subgroups with insulin resistance and without insulin resistance.ConclusionThis study showed protein oxidation in obesity with a novel oxidative stress marker and it also suggests that insulin resistance may play an important role as a source of oxidative stress in the development of other diseases after pubertal years.

Neck circumference as a novel parameter to determine metabolic risk factors in obese children.

Eur J Clin Invest 2012; 42 (6): 623–630

Reference Body Mass Index Curves for Turkish Children 6 to 18 Years of Age

AIM To determine reference body mass index (BMI) curves for Turkish children 6 to 18 years old and to compare with BMI in other countries. METHODS A cross-sectional study conducted in Kayseri, Turkey. A total of 5,727 children (2,942 girls, 2,785 boys) aged between 6 and 18 years were selected to construct a reference curve using LMS method. RESULTS BMI age reference charts of Turkish children were constructed. The 50th percentile curve of Turkish girls is lower than Italian and Turkish girls in The Netherlands but higher than Iranian girls. The 50th percentile curve of Turkish boys is lower than Italian and Turkish boys in The Netherlands and similar to Iranian boys after 13 years of age. CONCLUSION BMI references of Turkish children are lower than in South East Europe, UK and North American populations, but higher than in Central European and Scandinavian countries.

Percentiles and mean values for neck circumference in Turkish children aged 6-18 years.

Aim:  To provide neck circumference (NC) percentiles and mean values for Turkish children and to investigate their significance in clinical and epidemiological use.

Waist Circumference and Mid−Upper Arm Circumference in Evaluation of Obesity in Children Aged Between 6 and 17 Years

Objective: The purpose of this study was to determine the cut−off values for waist circumference (WC) and mid−upper arm circumference (MUAC) and to assess their use in screening for obesity in children. Methods: Anthropometric measurements of a total of 2621 boys and 2737 girls aged 6−17 years were analyzed. WC and MUAC values were compared with ROC analysis using body mass index (BMI) cut−off values of the International Obesity Task Force (IOTF) and using WC≥ 90th percentile.for MUAC. Results: In both genders, except for boys and girls in the 6−year age group and post−pubertal boys, the differences between area under curve (AUC) values for WC and MUAC were not significant, indicating that both indices performed equally well in predicting obesity. Sensitivity was suboptimal through age groups 6−9 years in the boys and sensitivity was suboptimal at 6, 7,14 and 17 years both in boys and girls. Conclusions: We conclude that MUAC can be a useful parameter in screening obesity and body fat distribution in children and, can be applied in epidemiological studies and in clinical practice. Conflict of interest:None declared.

Long-Term Treatment with n-3 Polyunsaturated Fatty Acids as a Monotherapy in Children with Nonalcoholic Fatty Liver Disease

Objective: To investigate the efficacy and safety of n-3 polyunsaturated fatty acids (PUFA) treatment in obese children with nonalcoholic fatty liver disease (NAFLD). Methods: One hundred and eight obese (body mass index (BMI) >95th percentile for age and sex) adolescents with NAFLD were included in the study. Mean age of the subjects was 13.8±3.9 years (9-17 yrs). The diagnosis of NAFLD was based on the presence of liver steatosis with high transaminases. The subjects were randomly divided into two groups. Group 1 (PUFA group, n=52) received a 1000 mg dose of PUFA once daily for 12 months and lifestyle intervention. Group 2 (placebo group, n=56) received a recommended diet plus placebo and lifestyle intervention for 12 months. Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA-IR) from fasting samples. Results: BMI, fasting insulin levels and HOMA-IR values in both groups decreased significantly at the end of the study. In group 1, 67.8% of the patients had a decrease from baseline in the prevalence of steatosis (p<0.001). Frequency of elevated alanine aminotransferase (ALT) levels (39.2% to 14.2%; p<0.01) and elevated aspartate aminotransferase (AST) levels (25% to 17.8%; p=0.01) decreased significantly in the PUFA group. Following a 12-month diet plus placebo and lifestyle intervention treatment, 40.3% (21) of the patients in the placebo group also showed a decrease in frequency of steatosis (p=0.04) and slight decreases in frequency of elevated ALT levels (38.4% to 28.8%; p=0.01) and AST levels (30.7% to 28.8%; p>0.05). Conclusion: Our results indicated that n-3 PUFA treatment is safe and efficacious in obese children with NAFLD and can improve ultrasonographic findings and the elevated transaminase levels.

Body Weight, Length and Head Circumference at Birth in a Cohort of Turkish Newborns

Objective: Intrauterine growth references are primarily useful indicators in the assessment of the general health status of newborn infants. Although Lubchenco’s references are still used in many neonatal care units, we believe that there is a need for up-to-date intrauterine growth references specific for different populations. To develop gestational age-and gender-specific national references for birth weight, birth length and head circumference. Methods: Data were collected from neonatal records of perinatology services of eleven hospitals from January to December 2009. The anthropometry of a total of 4750 singleton live births born between 28 and 41 weeks of gestation were recorded. Means and standard deviations were calculated, and percentiles for each gender and gestational week were produced using the LMS program. The results were compared with US infants and also with local data. Results: Gestational age- and gender-specific 3rd, 5th, 10th, 15th, 25th, 50th, 75th, 85th, 90th, 95th and 97th percentile values were produced. Comparison of the 10th, 50th and 90th percentile values showed that the boys were heavier and longer than the girls. Head circumference values were also higher in the boys. Proportions of small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) infants in the sample were 10.1%, 79.1% and 10.8%, respectively. Conclusion: These gender- and gestational age-specific references will be of use in clinical practice and also for research purposes until more comprehensive, reliable and accessible national data pertaining to the intrauterine growth of Turkish infants are produced. Conflict of interest:None declared.

Micropenis: Etiology, Diagnosis and Treatment Approaches

Micropenis is a medical diagnosis based on correct measurement of length. If stretched penile length is below the value corresponding to - 2.5 standard deviation of the mean in a patient with normal internal and external male genitalia, a diagnosis of micropenis is considered. Micropenis can be caused by a variety of factors including structural or hormonal defects of the hypothalamic-pituitary-gonadal axis. It can also be a component of a number of congenital syndromes. For the etiological evaluation, endocrinologic tests are important. This article reviews the etiology, diagnosis, treatment and management of micropenis. Conflict of interest:None declared.

Non-alcoholic fatty liver disease in obese children and the relationship between metabolic syndrome criteria.

AIM To investigate metabolic syndrome (MetS) and MetS criteria, and to establish whether metabolic syndrome criteria were associated with non-alcoholic fatty liver disease (NAFLD) in obese children. METHODS A total of 451 pubertal obese children (8-18 years old) were enrolled in the study. Patients were divided into three groups according to the degree of steatosis. Antropometric and laboratory measurements of the participants were recorded. RESULTS Of 451 obese children, 217 (48.1%) were diagnosed as having NAFLD and 96 (21.3%) as having MetS. The frequency of abdominal obesity, hypertension, impaired fasting glucose, hyperinsulinemia, dyslipidemia and type 2 diabetes mellitus (T2DM) were 61.8% (279), 25.7% (116), 4.4% (20), 54.3% (245), 41% (185) and 2.2% (10), respectively. The prevalence of NAFLD among patients with MetS [73% (70/96)], was significantly higher than the frequency of hypertension [55% (53/96)] and abnormalities of glucose metabolism [23% (22/96)], but almost equal to the frequency of dyslipidemia [78% (75/96)]. The prevalence of MetS criteria were higher in patients with NAFLD than those without NAFLD. Except impaired fasting glucose, blood pressure and T2DM significant difference was found between groups for all. It was observed that the number of MetS criteria increased in parallel with the severity of steatosis. CONCLUSION NAFLD in obese children is strongly associated with multiple MetS criteria. In addition to NAFLD is not only a liver disease, but also early mediator that reflects metabolic disorder, and liver ultrasound can be a useful tool for MetS screening.