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21-hydroxylase autoantibodies (21OHAb) are the gold standard immune marker to identify patients with clinical or subclinical autoimmune Addison's disease (AAD). No assessment of interlaboratory concordance has been made for 21OHAb measurement. Serum samples from 267 patients with primary adrenal insufficiency and from 83 healthy control subjects were distributed to four independent laboratories that determined presence and titer of 21OHAb, by using radiobinding assays with either in vitro translated 35S-radiolabelled or 125I-radiolabelled autoantigen. Cohen's κ of inter-rater agreement ranged from 0.857 to 0.983, showing a very good concordance of the positive/negative score among the four laboratories. Passing-Bablok regression showed a good agreement of 21OHAb titers arranged by ranks, but important discrepancies emerged at the Bland-Altman plot, as the repeatability coefficient was much higher than the laboratory cut-offs, which indicates that results from different laboratories cannot be used interchangeably. A standardization international program for 21OHAb measurement is strongly needed., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Objective: The prevalence of overweight and obesity was estimated among the school children and adolescents of three provinces of central Italy, and the role of several possible influencing factors was analysed., Design, Subjects and Measurements: Body mass index (BMI) was measured in 44 231 subjects, age 3-17.5 y, and a household questionnaire was filled out by the parents of 12 143 subjects to collect the following data: subjects, only child or firstborn status, prematurity, birth weight, type of feeding until the fifth month, menarche status in girls; parents, age at the time of the subject's birth; BMI (mean of the two parents) at the time the subject was measured, mother's age of menarche, socioeconomic status. BMI was measured in a subgroup of 10 795 subjects 1 y later to study the yearly sex- and age-related variations from the categories of normal weight to overweight or obesity and vice versa. All females aged 11-14 y were asked if they had their menarche., Results: Striking differences in the proportions of overweight and obesity resulted from the use of two different criteria for defining cutoff points. The overall prevalence of overweight was 13.2 and 20.7% in males, and 13.7 and 18.6% in females, and the overall prevalence of obesity varied between 24.2 and 6.3% in males, and between 22.9 and 6.1% in females, respectively. Parents' BMI, birth weight, firstborn status and post-menarche status in girls showed a significant association with overweight and/or obesity in logistic regression models., Conclusions: A large prevalence of overweight and obesity was observed in school subjects from three provinces of central Italy. From the comparisons of the prevalence rate, the new internationally agreed criteria seem more appropriate for epidemiological studies in this population., Sponsor: University of Perugia, Region of Umbria, Commune of Perugia.

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.