Evaluation of height prediction models: from traditional methods to artificial intelligence.

BACKGROUND: Traditional methods for predicting adult height (AHP) rely on manual readings of bone age (BA). However, the incorporation of artificial intelligence has recently improved the accuracy of BA readings and their incorporation into AHP models. METHODS: This study aimed to identify the AHP model that fits the current average height for adults in Mexico. Using a cross-sectional design, the study included 1173 participants (5-18 yr). BA readings were done by two experts (manually) and with an automated method (BoneXpert®). AHP was carried out using both traditional and automated methods. The best AHP model was the one that was closest to the population mean. RESULTS: All models overestimated the population mean (males: 0.7-6.7 cm, females: 0.9-3.7 cm). The AHP models with the smallest difference were BoneXpert for males and Bayley & Pinneau for females. However, the manual readings of BA showed significant interobserver variability (up to 43% of predictions between observers exceeded 5 cm using the Bayley & Pinneau method). CONCLUSION: Traditional AHP models relying on manual BA readings have high interobserver variability. Therefore, BoneXpert is the most reliable option, reducing such variability and providing AHP models that remain close to the mean population height. IMPACT: Traditional models for predicting adult height often result in overestimated height predictions. The manual reading of bone age is prone to interobserver variability, which can introduce significant biases in the prediction of adult height. The BoneXpert method minimizes the variability associated with traditional methods and demonstrates consistent results in relation to the average height of the population. This study is the first to assess adult height prediction models specifically in the current generations of Mexican children.

Muscle Strength Reference Values and Correlation with Appendicular Muscle Mass in Mexican Children and Adolescents.

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.

Bone Age Reading by DXA Images should not Replace Bone Age Reading by X-ray Images.

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.

Skeletal Maturation in the Current Pediatric Mexican Population.

OBJECTIVE: 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. METHODS: 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 (G&P) 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. RESULTS: The G&P and TW2 automated reference curves showed that Mexican boys exhibit delays in BA during middle childhood by 0.5 to 0.7 (95% confidence interval [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. CONCLUSION: Mexican children aged <10 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.

Risk Factors Associated with Nosocomial Peritonitis in Children on Peritoneal Dialysis.

BACKGROUND: Peritoneal dialysis is the most frequent dialysis method in children, and peritonitis is a frequent complication. The responsible organisms differ between nosocomial and community acquired peritonitis, they cause longer hospitalization time, and can lead to dialysis failure. OBJECTIVE: The aim of the study was to describe the risk factors associated with nosocomial peritonitis in children with end-stage renal disease undergoing dialysis treatment. METHODS: A nested case-control study was conducted in an academic medical center. SUBJECTS: The basic cohort included all pediatric patients with end-stage renal disease undergoing continuous ambulatory peritoneal dialysis therapy and who were hospitalized for non-infectious causes during the study period, January 2008 to December 2009. Cases were subjects who developed nosocomial peritonitis during hospitalization, and controls were children free of nosocomial peritonitis. The final groups consisted of 10 cases and 35 controls. RESULTS: There were 11 episodes of nosocomial peritonitis in 10 subjects (incidence rate, 6.6 cases per year of hospitalization). By multiple logistic regression analysis, the presence of congenital abnormalities of the kidney and urinary tract was the only risk factor significantly associated with nosocomial peritonitis (OR: 11.54; 95% CI: 1.86-71.59). CONCLUSION: Congenital abnormality of the kidney and urinary tract was a significant risk factor for nosocomial peritonitis in pediatric patients with end-stage renal disease undergoing peritoneal dialysis.

Association between bone age maturity and childhood adiposity.

BACKGROUND: Evidence shows that overweight and obesity are associated with advanced bone age (BA). OBJECTIVE: To analyse the effect of adiposity on BA among Mexican children. METHODS: This cross-sectional study included 902 children (5-18 years old). Anthropometric measurements, dual-energy X-ray absorptiometry (DXA) and automated hand X-ray-based BA measurements were obtained. BA curves of children stratified by sex and age were created based on nutritional status. We also calculated odds ratios for advanced BA associated with the body mass index (BMI), waist/height ratio and adiposity estimated using DXA (total and truncal fat mass). RESULTS: Participants with overweight/obesity by BMI (SDS ≥1) advanced earlier in BA than did normal weight participants (6.0 vs. 12.0 years in boys and 6.0 vs. 10.3 in girls, p < 0.01); similarly, participants with a greater body fat percentage (SDS ≥1) exhibited earlier advanced BA (7.5 vs. 10.0 years in boys and 6.0 vs. 9.6 in girls, p < 0.01). Differences were also observed according to the waist/height ratio and truncal fat. Children with a BMI or DXA SDS ≥1 had greater odds of presenting an advanced BA of more than 1 year (OR 1.79-3.55, p < 0.05). CONCLUSIONS: Increased adiposity in children, mainly in boys, is associated with advanced BA at earlier ages.

Body Composition Assessment in Mexican Children and Adolescents. Part 2: Cross-Validation of Three Bio-Electrical Impedance Methods against Dual X-ray Absorptiometry for Total-Body and Regional Body Composition.

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.

Body Composition Assessment in Mexican Children and Adolescents. Part 1: Comparisons between Skinfold-Thickness, Dual X-ray Absorptiometry, Air-Displacement Plethysmography, Deuterium Oxide Dilution, and Magnetic Resonance Imaging with the 4-C Model.

The evaluation of body composition (BC) is relevant in the evaluation of children's health-disease states. Different methods and devices are used to estimate BC. The availability of methods and the clinical condition of the patient usually defines the ideal approach to be used. In this cross-sectional study, we evaluate the accuracy of different methods to estimate BC in Mexican children and adolescents, using the 4-C model as the reference. In a sample of 288 Mexican children and adolescents, 4-C body composition assessment, skinfold-thickness (SF), dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), and deuterium dilution (D2O) were performed, along with MRI in a subsample (52 participants). The analysis of validity was performed by correlation analysis, linear regression, and the Bland-Altman method. All methods analyzed showed strong correlations for FM with 4-C values and between each other; however, DXA and MRI overestimated FM, whereas skinfolds and ADP under-estimated FM. Conclusion: The clinical assessment of BC by means of SF, ADP, DXA, MRI and D2O correlated well with the 4-C model and between them, providing evidence of their clinical validity and utility. The results from different methods are not interchangeable. Preference between methods may depend on their availability and the specific clinical setting.

Fracture incidence in children and adolescents 0-19 years old in Mexico: a 12-year cross-sectional analysis.

The objective was to know the behavior of fractures in Mexican children and adolescents. According to our study, fractures in Mexican male children and adolescents seem to be decreasing; however, we still need more national studies to know the possible causes of these fractures. PURPOSE: To describe the trends of fractures in Mexican children and adolescents across a 12-year period (2007 to 2019), and to analyze if these trends have changed over time between sexes and age groups. METHODS: We identified all fracture cases registered in children and adolescents (0 to 19 years) at the emergency rooms and surgical departments of the Mexican Institute of Social Security between January 2007 and December 2019. We used ICD-10 to classify the fractures. The population was divided into two age groups: children (0 to 9 years) and adolescents (10 to 19 years). Additional information regarding sex and age was gathered up as well. We calculated annual incidence; incidence rates are presented per 10,000 population at risk. Changes in fracture trends were calculated using the average annual percentage change (AAPC). RESULTS: Over 12 years, 1,400,443 fractures were registered. The most frequent site of fracture was forearm in 37.1% followed by shoulder (18.1%). The overall rates of fractures have remained similar over 12 years (86.5, IQR 81.0-94.2); however, a significant decrease in fractures was observed the last 3 years (2017-2019). According to the AAPC, only in men, in both age groups, a significant decrease in fractures was observed. CONCLUSION: This is the first study in Mexico to follow the behavior of fractures in the pediatric population over 12 years. Fractures seem to be decreasing in children and adolescents. An epidemiological follow-up of childhood fractures is necessary to understand the causes of fractures to generate better prevention and treatment strategies.

Vitamin D concentration and its association with parathyroid hormone in children and adolescents.

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.

Maternal Factors and Their Association with Patterns of Beverage Intake in Mexican Children and Adolescents.

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.

A Healthy Diet Is Not More Expensive than Less Healthy Options: Cost-Analysis of Different Dietary Patterns in Mexican Children and Adolescents.

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.

Reference values for bone mineral density in healthy Mexican children and adolescents.

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.

Correlation of appendicular muscle mass measured with dual-energy X-ray absorptiometry and anthropometry in a healthy population of pediatric and adolescent subjects.

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.

Introducción: Durante el proceso de crecimiento y desarrollo, los niños y adolescentes presentan cambios en su composición corporal. La masa muscular apendicular está relacionada con la movilidad, deambulación y, consecuentemente, con las actividades de la vida diaria. El objetivo del estudio fue determinar la correlación de la masa magra apendicular (MMA) de los miembros superiores e inferiores mediante absorciometría dual de rayos X (DXA) como método de referencia, en comparación con el área muscular apendicular (AMA) obtenida mediante antropometría. Métodos: Estudio transversal en niños y adolescentes sanos de 5 a 20 años de edad, residentes de la Ciudad de México y Área Metropolitana. Se incluyeron y midieron 1,081 sujetos clínicamente sanos. Resultados: La MMA obtenida con DXA y el AMA obtenida por antropometría tienen un coeficiente de determinación (r2) de 0.90. Al categorizarlos por percentil de índice de masa corporal, este se mantiene, aunque es ligeramente menor en el grupo de sujetos con obesidad, donde el coeficiente fue de r2 = 0.84. Conclusiones: La determinación de la masa muscular apendicular en niños y adolescentes mexicanos mediante antropometría es válida y precisa, y presenta una alta correlación con métodos como la DXA. La antropometría podría implementarse como parte de la evaluación de la masa muscular apendicular en el primer nivel de atención.

Obesogenic Lifestyle and Its Influence on Adiposity in Children and Adolescents, Evidence from Mexico.

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: "inactivity," "excessive screen time," "insufficient sleep," "unhealthy-diet", 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-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.

Bone age as a correction factor for the analysis of trabecular bone score (TBS) in children.

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.

Vitamin D, not iron, is the main nutrient deficiency in pre-school and school-aged children in Mexico City: a cross-sectional study.

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 (<50 nmol/l) was 24.77%. None of the children had haemoglobin levels below the anaemia threshold, and zinc determination revealed 8.26% of individuals with deficient levels (<65 µg/dL). These data confirm the findings reported in the latest National Nutrition Survey (ENSANUT 2012) about the sustained reduction of anaemia prevalence among preschool and schoolchildren since 1999 and the rising rates of vitamin D deficiency in the same population. Similar to other studies, we found a link between socioeconomic status and the deficiency of micronutrients, these being markers of better nutrition, and vitamin D is remarkably related to the quality of the diet. This finding has not been considered in our population before. CONCLUSIONS: There is evidence of a sustained decrease of anaemia in Mexican children due to general enrichment of foods and focus on vulnerable populations, while vitamin D deficiency seems to have increased. More studies are needed to obtain more information on vitamin D levels at different ages and definition of susceptible groups in order to investigate the possibility of general population measures such as enrichment, which have proven to be effective.

Vitamin D concentration and its association with parathyroid hormone in children and adolescents / Concentración de vitamina D y su relación con la hormona paratiroidea en niños y adolescentes

Abstract 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% of the 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 in this study are lower than those previously reported in Mexican children.

Resumen Introducción: La deficiencia de vitamina D se ha asociado inversamente con la concentración de hormona paratiroidea (PTH) en los adultos, pero no en los niños y adolescentes. El objetivo de este estudio fue reportar la concentración de vitamina D y su correlación con la concentración de PTH en una muestra de niños mexicanos sanos. Métodos: Se llevó a cabo un estudio transversal con 275 mexicanos sanos de 2 a 17 años de edad en quienes se estimaron las concentraciones de 25-(OH)-D utilizando cromatografía líquida con espectrometría de masas y de PTH por radioinmunoensayo, y su correlación. Resultados: Los participantes se categorizaron como prescolares (2 a 5 años), escolares (6 a 10 años) y adolescentes (11 a 17 años). La mediana de la concentración de 25-(OH)-D en los prescolares fue de 27.4 ng/ml, en los escolares de 25.6 ng/ml y en los adolescentes de 24.7 ng/ml. Solo en el 10.5% de los participantes se encontraron valores de vitamina D < 20 ng/ml. En contraste con el 10% de los escolares y el 21% de los adolescentes, solo el 3% de los prescolares mostraron deficiencia de vitamina D (p ≤ 0.05). La PTH se encontró dentro de los límites normales en el 95.6% de la población estudiada. Se encontraron concentraciones de vitamina D < 20 mg/dl en el 25.8% de los niños con sobrepeso y obesidad (p = 0.009). Conclusiones: Solo en el 10% de los participantes se encontraron concentraciones de vitamina D < 20 ng/ml, pero este porcentaje aumento con la edad y se hallaron valores < 20 ng/ml en el 21% de los adolescentes. La PTH se encontró dentro de los valores normales. Las concentraciones de vitamina D en este estudio resultaron menores que las previamente reportadas en niños mexicanos.

[Vitamin D deficiency in childhood: an opportunity for prevention]. / Deficiencia de vitamina D en la edad pediátrica. Una oportunidad de prevención.

The 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.

Correlación de la masa muscular apendicular medida por absorciometría dual de rayos X y antropometría en población pediátrica y adolescente sana / Correlation of appendicular muscle mass measured with dual-energy X-ray absorptiometry and anthropometry in a healthy population of pediatric and adolescent subjects

Resumen Introducción: Durante el proceso de crecimiento y desarrollo, los niños y adolescentes presentan cambios en su composición corporal. La masa muscular apendicular está relacionada con la movilidad, deambulación y, consecuentemente, con las actividades de la vida diaria. El objetivo del estudio fue determinar la correlación de la masa magra apendicular (MMA) de los miembros superiores e inferiores mediante absorciometría dual de rayos X (DXA) como método de referencia, en comparación con el área muscular apendicular (AMA) obtenida mediante antropometría. Métodos: Estudio transversal en niños y adolescentes sanos de 5 a 20 años de edad, residentes de la Ciudad de México y Área Metropolitana. Se incluyeron y midieron 1,081 sujetos clínicamente sanos. Resultados: La MMA obtenida con DXA y el AMA obtenida por antropometría tienen un coeficiente de determinación (r2) de 0.90. Al categorizarlos por percentil de índice de masa corporal, este se mantiene, aunque es ligeramente menor en el grupo de sujetos con obesidad, donde el coeficiente fue de r2 = 0.84. Conclusiones: La determinación de la masa muscular apendicular en niños y adolescentes mexicanos mediante antropometría es válida y precisa, y presenta una alta correlación con métodos como la DXA. La antropometría podría implementarse como parte de la evaluación de la masa muscular apendicular en el primer nivel de atención.

Abstract 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.