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Objective: To evaluate the dependence of body mass index (BMI) values on pubertal stage in subjects similar in age., Design, Subjects and Measurements: Height and weight were recorded cross-sectionally in school subjects from three provinces in central Italy. The subjects were subdivided into three groups: (1) 4271 school subjects (2125 males and 2146 females; 8.5-15.5 y old), in whom the pubertal development was also recorded, were selected to subdivide BMI values according to pubertal stage and age; (2) 6345 females (10.5-14.5 y old), who were asked whether or not they had had their first menstrual period, were selected to subdivide BMI values according to age in pre-menarche and post-menarche girls, separately; and (3) 1919 females (10.5-14.5 y old), who had presented their menarche within the previous 6 months, were selected to subdivide short-term post-menarche BMI values according to age., Results: The medians and interquartile ranges of BMI varied according to age and pubertal stage. Kruskall-Wallis test performed in subjects similar in age demonstrated that significant differences existed among the medians of BMI values of subjects at different pubertal stages in 12-14-y-old males (P<0.05), and in 11-14-y- old females (P<0.001). The difference also proved to be significant between stage I and stage II (P<0.05) in 10-y-old females, but not in 10-11-y-old males. The Kruskal-Wallis test performed in subjects similar in pubertal stage demonstrated that significant differences among the medians of BMI at different ages existed only in females at stages II and III. A significant positive trend was observed in both genders according to pubertal stage for BMI values of subjects similar in age (z-test for trend, P<0.01). On the contrary, a negative age trend proved to be significant in females at stages I (P<0.01), II (P<0.01) and III (P<0.001), but not in males when the subdivision of BMI was made according to age in subjects similar in pubertal stage. BMI values were significantly higher in post-menarche girls as compared to pre-menarche girls similar in age (P<0.001). However, at partial regression analysis BMI values were influenced by pubertal stage and, to a lesser extent, by age, but not by menarcheal status. An inverse association between short-term post-menarche BMI and age was observed, with the highest values in girls presenting menarche at 11 y of age (P<0.05). The negative trend was demonstrated at the z-test for trend (P<0.001)., Conclusions: BMI values depend on pubertal degree of maturation, especially in girls. This influence should be taken into account when BMI is evaluated in adolescents., Sponsor: University of Perugia, Region of Umbria.

Objective: Body mass index (BMI) was determined in a population of school students from three provinces of central Italy. Fasting serum leptin concentrations were assayed in a large number of subjects from the same area, to determine their distribution as plotted against the standard deviation score (z-score) of BMI., Design, Subjects and Measurements: Height and weight were recorded from 31170 subjects (16175 male and 14995 female), aged 3-18 y, to construct BMI charts of children and adolescents from central Italy. Percentiles and z-score were calculated using the LMS method of Cole. Serum leptin concentrations were assayed in 1929 subjects (996 male and 933 female) after overnight fasting., Results: BMI percentiles of central Italy were higher than those from standards of other European and USA populations. When plotted against the z-score of BMI, serum leptin values were distributed according to an exponential curve, showing a steep pattern and a wide distribution, as BMI values increased. The hypothesis of the existence of two subgroups, based on a different relation between leptin and BMI, was verified and a separation point between the two subgroups was identified using cluster analysis, discriminant analysis and a novel method developed by our group, hereafter referred to as 'regression clustering'. This method allows identification of the value of the independent variable (z-score of BMI) which can be taken as a separation point. This analysis provided the best results and indicated the following separation points: central Italy standard, z-score = 0.72 (76.4th percentile) for males and z-score = 0.69 (75.5th percentile) for females; French standard (the one suggested for a European population by the European Childhood Obesity Group, ECOG), z-score = 1.46 (92.8th percentile) for males and z-score = 1.96 (97.5th percentile) for females. Similar but variable results were obtained when the same analysis was performed on serum leptin concentration, subdivided according to pubertal development (stage I, stage II-III, stage IV-V)., Conclusions: Children and adolescents from central Italy had greater BMI percentiles when compared to other European populations. Fasting serum leptin concentrations showed a distribution pattern related to z-score, thus allowing to identification of two different subgroups. The z-scores of BMI, identified as separation points, indicated a trend to leptin production by adipocytes that could be taken as indicators of significant increases of fat mass. This study proposes criteria and a statistical approach that could be useful in the identification of BMI cut-off values when screening children and adolescents for overweight.

Aim To determine the influence of Type 1 diabetes mellitus on circulating adipocytokines in children. Methods The circulating concentrations of leptin, adiponectin, resistin and tumour necrosis factor (TNF)-α were measured in 91 children, aged 11.1 ± 2.7 years, with Type 1 diabetes mellitus (T1DM). Ninety-one healthy children were selected as control subjects. Results Body mass index-adjusted leptin concentrations were higher in the pubertal diabetic children compared with the control children. There was a significant positive correlation between leptin and daily insulin dose in the diabetic group. Circulating adiponectin concentrations were higher in the prepubertal diabetic children and were positively associated with HbA1c. Resistin concentrations were lower in the prepubertal non-diabetic subjects compared with the pubertal non-diabetic children, whose values were higher than those of the diabetic children. TNF-α concentrations were similar in non-diabetic and diabetic children. Conclusions Circulating concentrations of adipocytokines are abnormal in Type 1 diabetic children, although the direction of change differs by cytokine. Pubertal development, in addition to insulin treatment and glycaemic control, also influences the concentrations. [ABSTRACT FROM AUTHOR]