Context: No universal waist circumference (WC) percentile cutoffs used have been proposed for screening central obesity in children and adolescents. Objective: To develop international WC percentile cutoffs for children and adolescents with normal weight based on data from 8 countries in different global regions and to examine the relation with cardiovascular risk. Design and Setting: We used pooled data on WC in 113,453 children and adolescents (males 50.2%) aged 4 to 20 years from 8 countries in different regions (Bulgaria, China, Iran, Korea, Malaysia, Poland, Seychelles, and Switzerland). We calculated WC percentile cutoffs in samples including or excluding children with obesity, overweight, or underweight. WC percentiles were generated using the general additive model for location, scale, and shape (GAMLSS). We also estimated the predictive power of the WC 90th percentile cutoffs to predict cardiovascular risk using receiver operator characteristics curve analysis based on data from 3 countries that had available data (China, Iran, and Korea). We also examined which WC percentiles linked with WC cutoffs for central obesity in adults (at age of 18 years). Main Outcome Measure: WC measured based on recommendation by the World Health Organization. Results: We validated the performance of the age- and sex-specific 90th percentile WC cutoffs calculated in children and adolescents (6-18 years of age) with normal weight (excluding youth with obesity, overweight, or underweight) by linking the percentile with cardiovascular risk (area under the curve [AUC]: 0.69 for boys; 0.63 for girls). In addition, WC percentile among normal weight children linked relatively well with established WC cutoffs for central obesity in adults (eg, AUC in US adolescents: 0.71 for boys; 0.68 for girls). Conclusion: The international WC cutoffs developed in this study could be useful to screen central obesity in children and adolescents aged 6 to 18 years and allow direct comparison of WC distributions between populations and over time.

Background: The growth of children is an indicator of health and society's wellbeing. Growth references are useful in monitoring a child's growth, which is a very important part of child care. Poland's growth references are not updated regularly. Although several growth reference ranges have been developed in Poland over recent years, sampling was restricted to urban populations of major cities. The aim of this study was to assess how well Polish children match with, or diverge from, regional charts and to compare them with international growth references. Methods: Four Polish and two international (WHO 2007 and USCDC2000) growth references were used to calculate the height, weight and BMI z-scores in a recent, large, population-representative sample of school-aged children and adolescents in Poland. The distributions of z-scores were analysed with descriptive and inferential statistical methods. Results: Mean height z-scores calculated with the use of the WHO 2007 and USCDC2000 references were positive and significantly different from zero over the entire age range. The mean height z-score was closest to zero in the Poznan reference for boys (0.05) and Warszawa reference for girls (0.01). Median weight z-scores were positive under all weight references over the entire age range with only the exception of 18-year-old girls' weight z-score calculated relative to USCDC2000. Median BMI z-scores were positive in males in early childhood, decreasing with age. In the case of girls, the median BMI z-score calculated using WHO 2007 and USCDC2000 was close to zero in early childhood, decreased in adolescents and reached minimum values at age 18 years. Median BMI z-scores calculated with the use of the Lodz reference fluctuated between 0.05 and 0.2 over the studied age range. Conclusions: In this contemporary sample of Polish school-aged children, distributions of height, weight and BMI differed from those of children from the international growth references. These differences should be considered when using the references. There exist certain limitations to the analysis of height, weight, and BMI z-scores when Polish regional references are used.

Background: Resistance to thyroid hormone is characterised by a lack of response of peripheral tissues to the active form of thyroid hormone (triiodothyronine, T3). In about 85% of cases, a mutation in THRB, the gene coding for thyroid receptor β (TRβ), is the cause of this disorder. Recently, individual reports described the first patients with thyroid hormone receptor α gene (THRA) defects. Methods: We used longitudinal clinical assessments over a period of 18 years at one hospital setting combined with biochemical and molecular studies to characterise a novel thyroid hormone resistance syndrome in a cohort of six patients from five families. Findings: Using whole exome sequencing and subsequent Sanger sequencing, we identified truncating and missense mutations in the THRA gene in five of six individuals and describe a distinct and consistent phenotype of mild hypothyroidism (growth retardation, relatively high birth length and weight, mild-to-moderate mental retardation, mild skeletal dysplasia and constipation), specific facial features (round, somewhat coarse and flat face) and macrocephaly. Laboratory investigations revealed anaemia and slightly elevated cholesterol, while the thyroid profile showed low free thyroxine (fT4) levels coupled with high free T3 (fT3), leading to an altered T4 : T3 ratio, along with normal thyroid-stimulating hormone levels. We observed a genotype–phenotype correlation, with milder outcomes for missense mutations and more severe phenotypical effects for truncating mutations. Interpretation: THRA mutations may be more common than expected. In patients with clinical symptoms of mild hypothyreosis without confirmation in endocrine studies, a molecular study of THRA defects is strongly recommended.

Growth references are useful in monitoring a child's growth, which is an essential part of child care. The aim of this paper is to provide updated growth references for Polish preschool children and to assess how well children in Poland match or diverge from the World Health Organization (WHO) growth standards/references and recent German height-for-age references. The height-, weight-, body mass index-for-age, and weight-for-height references were constructed with the LMS method using data from a recent, large, population-representative sample of 4,941 preschool children aged 3 to 6 years (the OLA study). In the case of boys, the third, 50th, and 97th height percentiles of new Polish and German references overlap almost completely, whereas the WHO growth standards/references percentiles are systematically lower. In the case of girls, comparison between the new Polish and German height references showed conformity on the third and 50th percentile, whereas body height values of the WHO standards/references are shorter. Polish children aged 3 to 6 years from for the nation representative sample, had significantly greater than zero mean z scores of height-, weight-, and BMI-for-age and weight-for-height, relative to the WHO growth standards/references. The number of children in the sample with height-for-age below −2 SD was significantly lower than expected and number of children with height-for-age above +2 SD was significantly higher than expected. Conclusion: The OLA study growth references can be recommended as national references for preschool children in Poland.