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X-ray image of the hand is the most used technique to estimate bone age in children. For the analysis of bone mineral density using DXA in children, bone age may help to adjust such measurement in some cases. During image acquisition in DXA, an anteroposterior image of the hand may be acquired and used to evaluate bone age but few studies have evaluated the agreement between conventional X-ray and DXA images. The aim of the study was to determine bone age estimation agreement between conventional X-ray images and DXA in children and adolescents aged 5 to 16 years of age. We performed an analytical cross-sectional study of 711 healthy subjects. Subject´s bone age, both in conventional X-ray, and DXA images were read independently by two expert evaluators blinded for chronological age. Intraobserver and inter-observer reproducibility were evaluated using Intraclass Correlation Coefficient (ICC), and the agreement between bone age estimations made by both evaluators was analyzed using ICC and Bland-Altman analysis. General agreement between techniques measured through ICC was 0.99 with a mean difference of 6 months between techniques being older the ages obtained by DXA. The agreement limits were around ±2 years, which means that 95% of all differences between techniques were covered within this range. We found a high level of ICC agreement in bone age readings from X-ray and DXA images although we observed overestimation of bone age measurements in DXA. Differences between techniques were greater in women than in men, especially at the ages corresponding to puberty. Bone age measurement in DXA images appears not to be reliable; hence it should be suggested to perform conventional radiography of the hand to assess bone age taking into account that X-ray images have better resolution.

Phase angle (PhA) obtained by bioelectrical impedance analysis is a well-established predictor of malnutrition that reflects the amount and quality of soft tissue. However, PhA results may depend on configurations of the measurement that differ between devices. The aim was to analyze differences between devices for supine and standing measurements.In a cross-sectional study, differences in PhA were analyzed comparing supine vs. standing positions, metal vs. adhesive electrodes and the right vs. left side of the body in 302 multi-ethnic adults (18-65y) and 1298 Mexican children and adolescents (4-20y).PhA was higher in supine than in standing position (from 0.71°±0.22° in children to 0.97°±0.25° in adults; all p 0.001) with approximately fifty percent of observed differences explained by electrode placement. PhA differences increased with increasing PhA (r = 0.419) and decreased with age (r = -0.346) in adults, but increased with PhA (r = 0.677), age (r = 0.752) and height (r = 0.737) in children (all p 0.001). In adults, PhA was higher on the right side of the body (standing 0.18°±0.17°; supine 0.36°±0.33°; p 0.001).Phase angle results are influenced by posture and electrode placement. Measurement configuration must be considered when phase angle values are compared between different devices or with literature values.

The most commonly used methods for bone age (BA) reading were described in the Caucasian population decades ago. However, there are secular trends in skeletal maturation and different BA patterns between ethnic groups. Automated BA reading makes updating references easier and more precise than human reading. The objective of the present study was to present automated BA reference curves according to chronological age and gender in the Mexican population and compare the maturation tempo with that of other populations.The study included 923 healthy participants aged 5 to 18 years between 2017 and 2018. A hand radio-graph was analyzed using BoneXpert software to obtain the automated BA reading according to Greulich and Pyle (GP) and Tanner-Whitehouse 2 (TW2) references. We constructed reference curves using the average difference between the BA and chronological age according to sex and age.The GP and TW2 automated reference curves showed that Mexican boys exhibit delays in BA during middle childhood by 0.5 to 0.7 (95% confidence intervallsqb;CI], -0.9 to -0.2) years; however, they demonstrate an advanced BA of up to 1.1 (95% CI, 0.8 to 1.4) years at the end of puberty. Mexican girls exhibited a delay in BA by 0.3 to 0.6 (95% CI, -0.9 to -0.1) years before puberty and an advanced BA of up to 0.9 (95% CI, 0.7 to 1.2) years at the end of puberty.Mexican children aged10 years exhibited a delay in skeletal maturity, followed by an advanced BA by approximately 1 year at the end of puberty. This may affect the estimation of growth potential in this population.

Strength and muscle mass are important determinants of health status, and reference values for pediatric populations from every country or geographic region are needed. The aim of this study was to develop age- and sex-specific reference values of muscle strength and evaluate the correlation between muscle strength and appendicular lean mass in Mexican children and adolescents. A cross-sectional study was conducted in 1111 healthy subjects ages 5 to 19 years of age participating in the "Body Composition Reference Values in Mexican Children and Adolescents" study. Smoothed reference values for the 1, 3, 5, 15, 25, 50, 75, 85, 95, 97, and 99 percentiles of muscle strength for upper and lower limbs were developed based on age and sex using Jamar® and Microfet2® dynamometers. Mean values were derived using the Generalized Additive Models for Location, Scale and Shape (GAMLSS), and lean mass was determined using dual-energy X-ray absorptiometry. Highly positive correlations of muscle strength with lean mass in upper limbs were found r-values 0.87-0.92 for boys and r = 0.80-0.86 for girls. High and moderate positive correlations for lower limbs were also noted for upper limbs: r = 0.74-0.86 for boys and r = 0.67-0.82 for girls. The reference values for appendicular muscle strength established in this study demonstrated a high and positive correlation between appendicular mass and muscle strength. These data will be useful when evaluating conditions and diseases affecting muscle or sports.

The aim of our study was to validate three different bioelectrical impedance analysis (BIA) methods for estimating body composition (BC). First, we generated BIA prediction equations based on the 4-C model as the reference method for fat mass (FM) and fat-free mass (FFM), and on dual X-ray absorptiometry (DXA) estimations of appendicular lean mass (ALM) and truncal fat mass (tFM). Then, we performed cross-validation in an independent BMI-, sex-, and Tanner-stratified sample of 450 children/adolescents. The three BIA methods showed good correlation and concordance with DXA BC estimations. However, agreement analyses showed significant biases, with increasing subestimations of FM and tFM, and overestimations of ALM, by all three BIA methods. In conclusion, the three BIA methods analysed in this study, provide valid estimations of BC for total body and body segments, in children and adolescents who are of a healthy weight, overweight, or obese. It should be noted that this validation cannot be extrapolated to other BIA methods.

Background: Vitamin D (VD) deficiency has been inversely associated with parathyroid hormone (PTH) levels in the adult population but not in children and adolescents. This study aimed to report VD concentration and its correlation with PTH levels in a sample of healthy Mexican children. Methods: We conducted a cross-sectional study with 275 healthy Mexican subjects aged 2 to 17 years to estimate the status of 25-(OH)-D and its correlation with PTH levels. The 25-(OH)-D levels were estimated by liquid chromatography-tandem mass spectrometry and PTH by radioimmunoassay. Results: Subjects were categorized as young children (2 to 5 years), school children (6 to 10 years), and adolescents (11 to 17 years). The median concentration of 25-(OH)-D in young children was 27.4 ng/ml; in school children, 25.6 ng/ml; and adolescents, 24.7 ng/ml. VD levels < 20 ng/ml were found in only 10.5% of the participants. Only 3% of the young children showed VD deficiency, in contrast to 10% of school children and 21% of adolescents (p ≤ 0.05). PTH was found within normal ranges in 95.6% ofthe studied population. VD levels < 20 mg/dl were found in 25.8% of children with overweight or obesity (p = 0.009).Conclusions: VD levels < 20 ng/ml were observed in 10% of the studied group, but this percentage increased with age:21% of the adolescents showed VD levels < 20 ng/ml. No correlation with PTH levels was found. The VD values reported inthis study are lower than those previously reported in Mexican children.

Childhood and adolescence represent critical periods where beverage and food consumption behaviors are learned and developed. Mexican mothers’ presence and influence are instrumental in shaping such behaviors. The aim of this study was to estimate the prevalence and risk associations of maternal factors for unhealthy patterns of beverage intake. This study analyzed data from a population-based cross-sectional study of healthy children and adolescents from Mexico City. Data of subject’s total water intake (TWI) and its’ sources were collected using two 24-h recall surveys. Patterns of beverage intake were constructed based on the guidance system of beverage consumption in the US. Maternal factors of interest included age, body mass index (BMI), mother’s educational level (MEL), socioeconomic status (SES), and belongingness to the paid workforce (BPW). Data of 1532 subject–mother dyads informed that 47% of subjects did not meet the Institute of Medicine (IOM) recommendations for TWI, and 94.6% showed an unhealthy beverage intake pattern, mainly consisting in a lower intake of water and a higher intake of caloric beverages with some nutrients, and calorically sweetened beverages. The major sources of hydration were caloric beverages with some nutrients (i.e., whole milk, fruit water, and flavored milk). The highest risk association for an unhealthy beverage intake pattern was seen in those subjects with mothers in the cluster with lower SES, lower MEL, lower proportion of BPW, higher BMI, and younger age (OR = 9.3, 95% CI 1.2–72.8, P = 0.03). Thus, there is a remarkably high prevalence of an unhealthy pattern of beverage intake, and specific maternal factors may be implicated as enablers of such behaviors, which is also addressable for future interventions.

Background Children and adolescents present changes in their body composition during their growth and development process. The appendicular muscle mass (AMM) is related to mobility, ambulation and, consequently, with the activities of daily life. The objective of this study was to determine the correlation of the AMM of upper and lower limbs, obtained by dual X-ray absorptiometry (DXA), as a reference method compared to the appendicular muscular area (AMA) obtained by anthropometric measurements. Methods Cross sectional study in healthy children and adolescents from 5 to 20 years of age, residents of Mexico City and the Metropolitan Area. A total sample of 1081 clinically healthy subjects were included. Results The AMM obtained with DXA and the AMA obtained by anthropometry showed a coefficient of determination (r2) of 0.90. Categorizing by percentile of body mass index, the correlation is maintained, being slightly lower in the group of obese subjects, where the coefficient was r2 = 0.84. Conclusions Measurement of AMM in Mexican children and adolescents with anthropometry is a valid and accurate technic with a high correlation with methods such as DXA. Anthropometry could be implemented as part of the assessment of AMM in the first level care.

Overweight (OW) and obesity (OB) during childhood/adolescence are major public health problems in Mexico. Several obesogenic lifestyle (OL) risk factors have been identified, but the burden and consequences of them in Mexican children/adolescents remain unclear. The objective of this study was to estimate the prevalence of OL components and describe their relationships with adiposity, and OW/OB. A population-based cross-sectional study of Mexican children/adolescents with nutritional assessment, data collection on daily habits and adiposity as fat-mass index (FMI) by dual-energy X-ray absorptiometry was performed. Individual OL-components: &ldquo, inactivity,&rdquo, &ldquo, excessive screen time,&rdquo, insufficient sleep,&rdquo, unhealthy-diet&rdquo, were defined according to non-adherence to previously published healthy recommendations. Results: 1449 subjects were assessed between March 2015 to April 2018. Sixteen percent of subjects had all four OL-components, 40% had three, 35% had two, 9% had one, and 0.5% had none. A cumulative OL score showed a significant dose&ndash, response effect with FMI. The combination of inactivity, excessive screen time, and insufficient sleep showed the highest risk association to OW/OB and higher values of FMI. Conclusions: The prevalence of OL-components was extremely high and associated with increased adiposity and OW/OB. Several interventions are needed to revert this major public health threat.

Unhealthy diets are recognized as a major risk factor for many diseases. The decrease in costs of industrialized products, as well as the possible misinformation about a healthy diet, has led to new behaviors in the dietary patterns of the pediatric population. The costs of dietary patterns have not been estimated in our population, so the objective of this study was to determine the cost associated with dietary patterns in Mexican children and adolescents, hypothesizing that a healthy diet is not necessarily more economically expensive. This study analyzed data from a population-based cross-sectional study of healthy children and adolescents in Mexico City. Data were collected from a food frequency questionnaire and the meal cost of habitual food shopping. Eating patterns were obtained by using principal component analysis. A micro-costing technique was performed to obtain the direct costs of each pattern. When comparing the healthy pattern with the transition and non-healthy patterns, it was observed that there were no statistically significant differences between the dietary patterns (p = 0.8293). The cost of the healthy pattern only takes up 16.6% of the total biweekly income of a salaried Mexican. In this study, no differences were observed between the costs of a healthy and a less healthy diet.

Summary Trabecular bone score (TBS) is a tool to improve evaluation of DXA scans, barely used in children. We proposed to evaluate TBS with bone age (BA) compared to chronological age (CA). In girls, TBS value using BA is constant until age 8, and in boys until age 10, and then starts to increase steadily. This data may help widen TBS use in pediatric populations. Introduction Trabecular bone score (TBS) is a software-based tool for the analysis of DXA images to assess bone microarchitecture in the lumbar region. It is used widely in adults to improve evaluation of fracture risk, yet it has been rarely studied in children and no normal curves have been developed for pediatrics. The purpose of this study was to evaluate bone (skeletal) age compared to chronological age to determine which is better in the pediatric population since both bone age (BA) and trabecular density are equally susceptible to change in response to similar factors. Methods Total body, lumbar region, and non-dominant hand scans were obtained with an iDXA device in all participants. DXA scans of lumbar region for TBS analysis and AP images of non-dominant hand-for-BA were obtained for 565 children (269 female) aged 4to 19. Results Simple correlation was calculated and r2 values for TBS and chronological age were obtained by linear regression, with low correlations (0.36 for boys and 0.38 for girls), and then we created Loess curves to show the change for consecutive ages. In girls, the curve forms a U shape with a nadir point at approximately age 10. We then replaced chronological age with BA, and significant change was seen in the girls’ curve, where a turning point is seen at age 8. In boys, a similar trend shows a turning point at age 10. Finally, BA-corrected TBS curves were constructed using LMS, obtaining curves with percentiles. Conclusions The use of BA in the analysis and interpretation of TBS may help widen its use in pediatric populations by enabling the appearance of normative data, but more information is needed to confirm this finding.

Introduction Clinical assessment of bone health by Dual‐Energy X-ray Absorptiometry (DXA) in the paediatric population requires robust reference values. The International Society for Clinical Densitometry (ISCD) recommends that country/regional reference values ideally should be used to improve precision in bone health assessment. Objective The aim of this study was to provide reference values for relevant bone health variables for healthy Mexican children and adolescents aged 5 to 18 years. Methods This was a cross-sectional, stratified and population-based study, that measured a representative sample of healthy Mexican children and adolescents with DXA. We constructed age- and sex-smoothed reference values for areal bone mineral density (aBMD) of total body less head (TBLH), total body (TB), lumbar spine (LS), and bone mineral apparent density (BMAD) for LS, by means of Generalized Additive Models for Location, Scale and Shape (GAMLSS). Results Reference data including the 3th, 5th, 10th, 25th, 50th, 75th, 90th, 95th and 97th centiles, along with lambda (L), mu (M) and sigma (S) values, are given for each variable of interest for each sex at 0.25 years intervals. Reference values relative to height and Tanner-stage for both sexes are also provided. Finally, formulas to enable Z score estimation for clinical use are also presented Conclusions The sex, age, height, Tanner-stage and ethnic-specific reference data provided in this study should enable more precise assessment of bone health in the Mexican paediatric population. The data presented may also allow for future evaluation of potential similarities and differences across different ethnic groups.

ResumenLa prevalencia de deficiencia de vitamina D en la población pediátrica ha incrementado en los últimos años y se considera que continúa subdiagnosticada y subtratada. De acuerdo con datos de la Encuesta Nacional de Salud y Nutrición 2006, en México se ha estimado una prevalencia del 16% en niños de 2 a 12 años. La vitamina D desempeña un papel fundamental en la formación y homeostasis del hueso, y consecuentemente en el crecimiento. Su deficiencia se asocia con enfermedades como raquitismo y osteomalacia, y se ha relacionado con otros padecimientos, como obesidad, síndrome metabólico, diabetes, cáncer, infecciones de vías respiratorias y problemas del sistema inmune. En la literatura se han descrito grupos específicos de riesgo para deficiencia de vitamina D en los que el suplemento pudiera ofrecer un beneficio. Actualmente aún hay controversia en definir los niveles séricos de suficiencia, así como la dosis de suplemento. En México, la ingesta diaria sugerida de vitamina D es de 5.6μg/día (224 UI), que resulta significativamente menor a las recomendaciones en los Estados Unidos y Europa (entre 400 y 1,000 UI). Debido al aumento en la deficiencia de vitamina D en los últimos años y a la falta de consenso con respecto a los niveles de suficiencia de vitamina D (ya que los valores de corte varían de 20 a 30ng/ml considerados por la asociación de endocrinología), el objetivo de esta revisión fue proporcionar un panorama general del problema en la población pediátrica, así como describir aquellos grupos en riesgo y analizar las recomendaciones vigentes para el suplemento de vitamina D.La deficiencia de vitamina D se ha considerado rara en México, y la falta de evidencia no ha permitido establecer las recomendaciones de ingesta diaria, de acuerdo con el Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Sin embargo, hoy debe reconocerse como un problema de salud, meritorio de atención y acción. Sugerimos que se lleven a cabo estudios prospectivos en nuestro país, donde se establezca la relación entre la deficiencia sérica de vitamina D y la pobre mineralización ósea.AbstractThe prevalence of vitamin D deficiency in the pediatric population has increased in recent years and continues to be underdiagnosed and undertreated. According to data from the “ENSANUT 2006” (National Health and Nutrition Survey), the prevalence of vitamin D deficiency in Mexico was 16% in children aged 2-12 years. Vitamin D plays a critical role in the formation and bone homeostasis and consequently on growth. Its deficiency is clearly associated with diseases such as rickets and osteomalacia, and it has been linked to other diseases such as obesity, metabolic syndrome, diabetes, cancer, respiratory infections and immune system disease. Specific risk groups have been described in the medical literature for vitamin D deficiency in which supplementation may offer a benefit. Currently, there is still controversy in defining the serum levels of proficiency and dose supplementation. In Mexico, the daily suggested intake of vitamin D is 5.6μg (224 IU), which is significantly lower than the recommendations in the U.S. and Europe (i.e., between 400 and 1000 IU/day).An increase in vitamin D deficiency has been reported in recent years. There is no consensus regarding the sufficiency levels of vitamin D. Cut-off values vary from 20 to 30ng/ml. Therefore, the objective of this review was to provide an overview of the problem in the pediatric population and to describe the groups at risk, as well as to analyze the current recommendations for vitamin D supplementation.Vitamin D deficiency was considered rare in Mexico according to the National Institute of Medical Science and Nutrition Salvador Zubirán. Lack of evidence did not help to establish the international recommended daily intake. Currently, vitamin D deficiency must be recognized as a health problem, worthy of attention and action. We suggest that prospective studies are carried out in our country where the relationship between serum vitamin D deficiency and poor bone mineralization will be established.

The accumulation of abdominal fat is associated with cardiometabolic abnormalities. Waist circumference (WC) measurements allow an indirect evaluation of abdominal adiposity. However, controversy exists over which WC reference values are the most suitable for identifying the pediatric population at risk. The aim of the study was to evaluate the ability of various WC indices to identify abdominal obesity as diagnostic tools for predicting cardiometabolic risk in Mexican children and adolescents.Anthropometric measurements were performed and biochemical profiles determined in a crosssectional study that included 366 children and adolescents. Four parameters were used to evaluate abdominal obesity in our study group: (1) WC90th percentile, according to the Fernández reference in a Mexican-American population measured by the National Center for Health Statistics (NCHS) technique; (2) WC90th percentile, according to the Klünder reference in a Mexican population (measured by the World Health Organization [WHO] technique); (3) waist-to-height ratio (WHtR)0.5 according to WHO; and (4) WHtR0.5 according to NCHS. The ability of each of the indices to discriminate cardiometabolic abnormalities (fasting plasma glucose, dyslipidemia, and hypertension) was assessed.WHtR0.5 according to WHO or NCHS references showed greater sensitivity to detect metabolic abnormalities compared to percentile reference parameters (74.3 to 100% vs. 59.0 to 88.9%; P.05). However, the percentiles displayed more specificity to identify these alterations (46.2 to 62.2 vs. 21.3 to 46.9; P.05). Area under the curve analysis showed that WHtR0.5 can more readily detect hypertriglyceridemia (0.642), hypoalphalipoproteinemia (0.700), and a combination of two or more metabolic abnormalities (0.661), whereas WC90th percentile, according to Klünder, better detected hyperglycemia (0.555).WHtR0.5 is a sensitive measure to identify pediatric patients with cardiometabolic alterations, despite its low specificity, and is a useful diagnostic tool to detect populations at risk. Based on the results of this study, we recommend preferential use of the Klünder waist circumference references over the Fernández method in Mexican pediatric populations.AUC = area under the curve BMI = body mass index HDL = high-density lipoprotein IDF = International Diabetes Federation LDL = low-density lipoprotein MS = metabolic syndrome NCHS = National Center for Health Statistics ROC = receiver operating characteristic WC = waist circumference WHO = World Health Organization WHtR = waist-to-height ratio.

Introduction: In 2012, the Mexican National Health Survey showed a moderate prevalence rate of vitamin D deficiency, around 16%, in a national representative sample of children. A decreasing prevalence of anemia during the last 15 years has been observed in Mexico. The aim of this study was to determine the levels of vitamin D in children 3–8 years old in four different locations within the metropolitan area of Mexico City and to compare them to levels of iron and zinc as references of nutritional status.Methods: One hundred and seventeen healthy children aged 3–8 years attending four hospitals in Mexico City were invited to participate. All children received medical and nutritional evaluation, and blood samples were obtained.Results: Children were selected in the four hospitals between April and August 2008. More than half (51.3%) were boys; their average age was 5.5 ± 1.6 years. The mean height and weight of the children were 112.1 ± 11.2 cm and 20.2 ± 4.9 kg respectively, with a body mass index [BMI] of 15.8 ± 1.7 kg/m². The mean Z-score (BMI) was 0.007 ± 0.999. The prevalence of subjects with deficient levels of 25-OH-vitamin D (