Association between Urinary Sodium Excretion and Body Fat in School-Aged Children: Insights from the ARIA Study.

Childhood obesity has been associated with increased sodium intake. Nonetheless, evidence linking sodium intake to Body Mass Index (BMI) and Body Fat Mass Percentage (%BF) remains limited, especially in the pediatric age group. Therefore, this study aims to investigate whether there is an association between 24 h urinary sodium excretion with BMI and %BF in a sample group of children from the ARIA study. This cross-sectional analysis included 303 children aged 7 to 12 from across 20 public schools in Porto, Portugal. Weight and %BF were assessed using the Tanita™ BC-418 Segmental Body Analyzer. Children's Total Energy Intake (TEI) was estimated through a single 24 h Recall Questionnaire, and urinary sodium and potassium excretion was estimated by a 24 h urine collection. The association of %BF and BMI with 24 h sodium excretion was estimated by a binary logistic regression adjusted for sex, age, physical activity, total energy intake, parental education, and 24 h urinary excreted potassium. There was a significant positive association between higher levels of urinary sodium excretion and higher %BF values, even after adjusting for confounders. However, the same was not observed for BMI. Our findings suggest that higher sodium intake is associated with higher values of %BF among children, regardless of TEI and potassium intake.

Beta cell function, incretin hormones, and incretin effect in obese children and adolescents with prediabetes.

BACKGROUND: Defects of incretin hormones and incretin effect may be underlying mechanisms of abnormal glucose metabolism in youth. OBJECTIVE: To assess incretin hormone dynamics during an oral glucose tolerance test (OGTT) and incretin effect in obese children with prediabetes in comparison with those with normal glucose tolerance (NGT). METHODS: Overweight and obese children were enrolled and classified according to OGTT results as NGT and prediabetes. Insulin sensitivity, insulin secretion, incretin hormone concentrations during OGTT; and incretin effect derived from OGTT and intravenous glucose tolerance test were determined and compared between NGT and prediabetes groups. RESULTS: Sixty-three patients (43 NGT and 20 prediabetes) were enrolled. Their median (interquartile range) age was 12.5 (11.1, 13.8) years. Peak glucagon-like peptide-1 (GLP-1) was demonstrated at 30 min during OGTT and was higher in the prediabetes group (49.2 [35.6, 63.6] versus 36.5 [27.6, 44.2] pmol/L, p = 0.009). However, incremental areas under the curves (iAUCs) of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) were not different between the two groups. There was no difference in incretin effect between NGT and prediabetes (NGT: 66.5% [60.2%, 77.5%] vs. prediabetes: 70.0% [61.5%, 75.0%], p = 0.645). Incretin effect had positive correlations with iAUCs of both GLP-1 and GIP (GLP-1: r = 0.40, p = 0.004 and GIP: r = 0.37, p = 0.009). CONCLUSIONS: Comparing between obese children with prediabetes and NGT, there were no differences in overall incretin hormone changes during OGTT and incretin effect. Incretin effect was positively correlated with iAUCs of GLP-1 and GIP.

Urinary NGAL is a Potential Biomarker for Early Renal Injury in Insulin Resistant Obese Non-diabetic Children

Objective: Neutrophil gelatinase-associated lipocalin (NGAL) is one of the new biomarkers for detecting acute renal injury. There are studies showing the relationship between NGAL and renal injury in obese children. The aim of this study was to investigate whether urinary levels of NGAL, kidney injury molecule-1, and serum cystatin C are increased in insulin resistance (IR) patients before the development of diabetes. Methods: Cross-sectional, case-controlled study that included non-diabetic obese children and adolescent patients with IR and a non-diabetic obese control group with no IR, who attended a tertiary center pediatric endocrinology outpatient clinic between 2016-2018. Those with diabetes mellitus and/or known renal disease were excluded. NGAL and creatinine (Cr) levels were evaluated in the morning spot urine from all participants. Serum renal function was evaluated. Results: Thirty-six control and 63 IR patients were included in the study, of whom 68 (68.7%) were girls. The mean age of all participants was 13.12±2.64 years and no statistically significant difference was found between the two groups in terms of age or gender distribution. Median (range) spot urinary NGAL (u-NGAL) values in the IR group were significantly higher at 26.35 (7.01-108.7) ng/mL than in the control group at 19.5 (3.45-88.14) ng/mL (p=0.018). NGAL/Cr ratio was also significantly higher in the IR group compared to the control group (p=0.018). Conclusion: Obese pediatric patients with IR were shown to have elevated levels of u-NGAL, a marker of renal injury. u-NGAL examination may show early renal injury before development of diabetes.

Urinary bisphenol A levels in prepubertal children with exogenous obesity according to presence of metabolic syndrome.

OBJECTIVES: Recent studies have shown a potential link between chronic exposure to Bisphenol A (BPA) and exogenous obesity, the prevalence of which has been increasing dramatically in all age groups and particularly among children in the last decades. In this study, we aimed at comparing BPA exposure levels between controls and otherwise healthy, drug-naive, pre-pubertal children having exogenous obesity with/without metabolic syndrome. METHODS: A total of 63 pre-pubertal children with exogenous obesity whom 27 of them having metabolic syndrome attending Hacettepe University Ihsan Dogramaci Children's Hospital were included in this study. The control group consisted of 34 age- and sex-matched healthy children with no significant underlying medical conditions. Urinary BPA levels were measured using LC-MS/MS (high-performance liquid chromatography coupled with tandem mass spectrometry) methodology. RESULTS: Urinary BPA levels among obese children were significantly higher than those of the control group (median: 22.9 µg/g-creatinine and 6.9 µg/g-creatinine, respectively; p=0.0001). When adjusted with generalized linear models for age, gender and z scores of body mass index, obese children having metabolic syndrome had significantly higher urinary BPA levels than obese children without metabolic syndrome and both obese groups had considerably elevated levels of urinary BPA than the controls (estimated marginal mean ± standard error: 42.3 ± 7.4 µg/g-creatinine, 22.6 ± 3.5 µg/g-creatinine and 12.1 ± 2.5 µg/g-creatinine, respectively, p=0.0001). CONCLUSIONS: This study shows much higher BPA exposure among obese children with metabolic syndrome during the prepubertal period.

Obesity and Monitoring Iodine Nutritional Status in Schoolchildren: is Body Mass Index a Factor to Consider?

Background: The frequency of overweight (OW) and obese (OB) children has increased worldwide, particularly in economically developed countries. No studies have been conducted to verify whether the increasing frequency of OW and obesity in schoolchildren may affect the evaluation of iodine nutritional status in populations. The aim of this study was to verify whether urinary iodine concentration (UIC), thyroid volume (TV), and thyroid hypoechoic pattern may be affected by body mass index (BMI) in schoolchildren. Methods: The children included in this study (aged 11-13 years) were a part of the schoolchildren recruited in the second nationwide survey (period 2015-2019) conducted in Italy to monitor by law (Atto di Intesa Stato-Regioni February 26, 2009) the nationwide iodine prophylaxis program. Specifically, 1281 schoolchildren residing in iodine-sufficient areas (IS group) and 384 children residing in a still mildly iodine-deficient area (ID group) were recruited between January and March 2015 in the first-degree secondary state schools. In all the children, spot UIC was measured, thyroid ultrasound was performed to evaluate TV, and hypoechogenicity was assessed to indirectly evaluate iodine-associated thyroid autoimmunity. Results: The frequency of OW, OB, and adequate weight (AW) children was similar in the IS and ID groups at any age. After adjusting for sex and age, the regression analysis showed lower UIC values in OB children than in AW children of the IS group (beta coefficient = -34.09 [95% confidence interval -65.3 to -2.8]), whereas no significant differences were observed in the ID group. In both the IS and ID groups, the distribution of TV in AW children was significantly shifted toward lower values in comparison to the distribution of OB children (p < 0.001 in the IS group; p = 0.012 in the ID group). Furthermore, the frequency of thyroid hypoechogenicity was higher in the ID group than in the IS group (10.9% vs. 6.6%, p = 0.005); however, in both groups, it was significantly lower in AW children than in OB children (p < 0.01). Conclusions: This study for the first time demonstrates that BMI may be a confounding factor in monitoring iodine nutritional status in schoolchildren. Since in Italy as in other Western countries the number of OW and OB children is high, BMI is a factor to consider in monitoring salt iodization programs worldwide.

Association of urinary polycyclic aromatic hydrocarbons and obesity in children aged 3-18: Canadian Health Measures Survey 2009-2015.

Polycyclic aromatic hydrocarbons (PAHs) may contribute to obesity. Childhood obesity is a strong predictor of adult obesity and morbidity; however, the relationship between PAHs and obesity in young children (e.g., aged 3-5) has not been studied. We examined the association between urinary PAH metabolites and measures of obesity in children. We analyzed data from 3667 children aged 3-18 years who participated in the Canadian Health Measures Survey (CHMS, 2009-2015). We ran separate multivariable linear models to estimate the association between quartiles of PAH metabolites and each of body mass index (BMI) percentile, waist circumference (WC), and waist-to-height ratio (WHtR) in the total population, as well as in the age subgroups 3-5, 6-11, and 12-18, adjusting for age, sex, ethnicity, education, income quintile, diet, creatinine, and exposure to environmental tobacco smoke. A multinomial logistic regression model estimated adjusted odds ratios for risk of central obesity. BMI, WC, and WHtR were positively associated with total PAH and naphthalene metabolites in the total population aged 3-18 and in age groups 6-11 and 12-18. In 3-5 year olds, WHtR, but not BMI, was significantly associated with total PAH, naphthalene, and phenanthrene metabolites. Overall, those in the highest quartile for naphthalene or total PAH metabolites had three times greater odds of having central obesity compared with those in the lowest quartile. Urinary PAH metabolites are associated with WHtR, an indicator of central obesity and predictor of health risks associated with obesity, in children as young as 3-5.

Nonalcoholic Fatty Liver Disease (NAFLD), But not Its Susceptibility Gene Variants, Influences the Decrease of Kidney Function in Overweight/Obese Children.

: Nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of kidney disease in adults and children. However, it is uncertain whether this association is influenced by major NAFLD susceptibility genes. In a sample of 230 overweight/obese children, 105 with NAFLD (hepatic fat fraction ≥5% by magnetic resonance imaging) and 125 without NAFLD, rs738409 in PNPLA3, rs58542926 in TM6SF2, rs1260326 in GCKR, and rs641738 in MBOAT7 were genotyped. Abnormal kidney function was defined as estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m2 and/or the presence of microalbuminuria (24 h urinary albumin excretion between 30 and 300 mg). In comparison with children without NAFLD, those with NAFLD showed increased prevalence of reduced eGFR (13.3% vs. 1.6%; p < 0.001) and microalbuminuria (8.6% vs. 3.4%, p = 0.025). TM6SF2, GCKR, and MBOAT7 risk alleles did not show any impact on kidney function, while the PNPLA3 G allele was associated with lower eGFR, but only in children with NAFLD (p = 0.003). After adjustment for confounders, NAFLD (OR, 4.7; 95% CI, 1.5-14.8; padj = 0.007), but not the PNPLA3 gene variant, emerged as the main independent predictor of renal dysfunction. Overall, our findings suggest that NAFLD remains the main determinant of decline in kidney function in overweight/obese children, while the PNPLA3 rs738409 prosteatogenic variant has a small impact, if any.

Serial cross-sectional study for the association between urinary bisphenol A and paediatric obesity: Recent updates using NHANES 2003-2014.

BACKGROUND: Several studies have reported bisphenol A (BPA) as a potential risk factor for paediatric obesity, but the findings were inconsistent among these studies. METHODS: Using data from the National Health and Nutrition Examination Survey from 2003 to 2014, we conducted a serial cross-sectional study to examine the association between urinary BPA and paediatric obesity among children aged 6 and 19 years. The association between paediatric obesity and urinary BPA concentrations with or without urinary creatinine adjustments was assessed using multivariable regression and cubic spline models fitted for regression models. RESULTS: We observed decreasing trends in urinary BPA concentrations from 2003 to 2014. The associations between urinary BPA concentrations and obesity were inconsistent across the years of survey and even after different models for urinary creatinine adjustments were used. Children with obesity were positively associated with urinary creatinine concentrations, but was not with creatinine-adjusted models. Furthermore, children with higher urinary BPA concentrations had elevated odds of obesity during 2003 to 2008, whereas these associations were inconsistent during 2009 to 2014. CONCLUSIONS: The associations between paediatric obesity and urinary BPA concentrations differed across the years of survey and creatinine adjustments. Further studies are required to assess these discrepancies.

Identifying Pathways Mediating Obstructive Sleep Apnea and Obesity in Indian Children.

OBJECTIVE: Overweight and obesity in children is associated with several metabolic and cardiovascular impairments, including obstructive sleep apnea (OSA). However, the causal pathway from OSA to obesity is not fully known yet. The aim of this study was to explore the association between OSA and obesity-related metabolic outcomes in obese Indian children. METHODS: An observational, cross-sectional study was conducted. Obese children referred to the Otorhinolaryngology Department at the Maulana Azad Medical College (New Delhi, India) for suspicion of OSA were consecutively enrolled. OSA was diagnosed by polysomnographic parameters. Homeostasis model assessment (HOMA) was calculated to measure insulin sensitivity and HOMA > 4.39 was considered as a threshold for insulin resistance. The association between various polysomnographic measures and HOMA, adiponectin and various urinary catecholamines was assessed. RESULTS: Complete polysomnographic parameters were available for 45 children; of these 29 were found to suffer from OSA. OSA children had significantly higher glucose concentrations compared to non-OSA ones (p value = 0.012) but no differences were found in insulin resistance and urinary catecholamines levels. Older age was significantly associated to lower levels of catecholamines. No significant associations were found between polysomnographic parameters and both HOMA and adiponectin. Only age was found to be significantly associated with HOMA (p = 0.03) and adiponectin (p = 0.01). CONCLUSIONS: A better understanding of the role played by OSA on obese children's metabolic functions is crucial to implement specific prevention strategies to reduce the public health burden of non-communicable diseases.

24-h urinary sodium to potassium ratio and its association with obesity in children and adolescents.

PURPOSE: There are epidemiologic studies indicating a positive correlation between high sodium and low potassium intake and body mass index. Therefore, this study was conducted in a cross-sectional sample of Iranian children and adolescents to evaluate the link between 24-h urinary Na:K ratio and risk of obesity. METHODS: In this cross-sectional study, 374 participants aged 11-18 years were included. One 24-h urine sample was collected by each participant to estimate Na:K ratio. Anthropometric measurements were carried out and overweight/obesity was defined as a BMI ≥ 85th percentile and abdominal obesity as a waist:height ratio (WHtR) of more than 0.5. RESULTS: As expected, 24-h urinary Na:K ratio showed significant associations with risk of overweight/obesity. Risk of adiposity assessed by WC and PBF was significantly associated with Na:K ratio after adjusting for SSBs consumption and calorie intake. Urinary Na:K ratio showed significant association with risk of adiposity assessed by WC only in girls in the highest tertile group with OR of 2.71 (95% CI 1.14-6.43), only after the addition of calorie intake. Adiposity assessed by PBF was only associated with Na:K ratio among boys with OR of 4.47 (95% CI 1.44-9.87) and 3.87 (95% CI 1.20-8.48), after adjusting for SSBs consumption and calorie intake, respectively. CONCLUSION: Our findings suggest that reducing Na and increasing K intake could be used as a useful approach to lower the risk of obesity and associated burden of disease in Iran. However, more studies are warranted.

Association of polycyclic aromatic hydrocarbons with cardiometabolic risk factors and obesity in children.

A limited body of evidence exists on the association of exposure to polycyclic aromatic hydrocarbons (PAHs) with cardiometabolic risk factors and obesity in children. No study has evaluated these associations in subgroups of children with and without excess weight, and those with and without cardiometabolic risk factors. We aimed to investigate the association between PAH exposure and cardiometabolic risk factors in children independent of their weight status. The secondary aim was to evaluate the obesogen properties of PAHs in children independent of their cardiometabolic risk factors. This study was based on a representative sample of 186 children (aged 6-18 years) living in Isfahan, Iran (2014-2016). We enrolled four groups of participants with and without excess weight and with and without cardiometabolic risk factor. Urinary levels of monohydroxy PAHs (OH-PAHs) were measured twice, six months apart. Logistic regression models were developed to estimate the associations of tertiles of urinary OH-PAH concentrations with cardiometabolic risk factors and excess weight, adjusted for the relevant covariates. The findings in all participants combined showed that increased risk of cardiometabolic risk factors and excess weight was associated with exposure to most of evaluated PAHs. Exposure to 1-hydroxypyrene was associated with higher risk of cardiometabolic risk factors in participants with excess weight. Exposure to 2-Naphtol was also associated with higher risk of cardiometabolic risk factors in both groups, but the associations were not significant (p < 0.1). For participants without cardiometabolic risk factors, exposure to 2-naphtol, 9-phenanthrol, and ∑ OH-PAH was associated with increased risk of obesity. For participants with cardiometabolic risk factors, we observed similar pattern of associations for 2-naphtol and ∑ OH-PAH, but the associations were not statistically significant (p < 0.1). We found that exposure to PAHs could possibly explain, in part, the cardiometabolic risk factors in children with excess weight as well as obesity in children with normal cardiometabolic profile.

Effect of bariatric surgery on urinary sphingolipids in adolescents with severe obesity.

BACKGROUND: Untreated severe obesity of adolescents is associated with abnormal kidney function and development of chronic kidney disease. Lipotoxicity due to lipid accumulation in glomeruli might be an important mechanism in the progression of kidney disease in obesity. OBJECTIVE: To assess subclinical glomerular injury by measuring urinary sphingolipids in adolescents with severe obesity before and after weight loss surgery. We hypothesized that the levels of urinary sphingolipids would be elevated at baseline and improve after weight reduction. SETTING: Cincinnati Children's Hospital Medical Center, University of Cincinnati. METHODS: Ten adolescents undergoing bariatric surgery with no microalbuminuria and normal kidney function were selected. Urinary sphingolipids (ceramides, glycosphingolipids, and sphingomyelins) were quantified using ultra performance liquid chromatography electrospray ionization tandem mass spectrometry at baseline and 1 year postoperatively. The levels of sphingolipids were compared with lean and moderately obese controls. RESULTS: Participants with severe obesity had a mean baseline body mass index of 50 kg/m2 that decreased to 36 kg/m2 at 1 year postsurgery (28% reduction). Almost all urinary ceramides, glycosphingolipids, and sphingomyelin species were significantly elevated in participants with severe obesity compared with controls at baseline (P<.01). One year after weight loss surgery, levels of urinary sphingolipids improved but were still significantly elevated compared with controls. CONCLUSIONS: Our study indicates that severe obesity is associated with increased urinary excretion of sphingolipids despite the absence of microalbuminuria or decreased kidney function. Urinary sphingolipids may therefore represent a marker of early (subclinical) glomerular injury in adolescents with severe obesity.

Association of urinary concentrations of four chlorophenol pesticides with cardiometabolic risk factors and obesity in children and adolescents.

This study was undertaken to determine the association of four chlorophenol pesticides with cardiometabolic risk factors and obesity in children and adolescents. This cross-sectional study was conducted in 2016 on 242 children and adolescents, aged 6 to 18 years. The concentrations of 2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), 2,4,5-trichlorophenol (2,4,5-TCP), and 2,4,6-trichlorophenol (2,4,6-TCP) in the urine were examined and their association with indices of obesity and cardiometabolic risk factors was determined. Multivariate linear regression and multinomial logistic regression analyses were applied. Overall, 242 participants with mean (SD) ages of 11.3 (2.5) years completed the survey. After adjustment for confounders, a significant positive association was found between body mass index (BMI) z-score and waist circumference (WC) with 2,5-DCP (0.07 (95% CI 0.04, 0.1)) and 0.79 (95% CI 0.54, 1.03), respectively. A significant association of 2,4,5-TCP was only found with WC (0.23 (95% CI 0.0, 0.46), but the relationship with 2,4-DCP was not significant. 2,5-DCP had a significant relationship only with obesity (1.09 (95% CI 1.1, 1.19)), while 2,4-DCP and 2,4,5-TCP showed no significant correlation with overweight or obesity. 2,4-DCP showed a significant positive relationship with high density lipoprotein-cholesterol (HDL-C). Moreover, 2,5-DCP showed a significant negative relationship only with systolic blood pressure and 2,4,5-TCP had a statistically significant inverse association with total cholesterol and HDL-C (-0.71 (95% CI -0.98, -0.45)). This study suggests potential associations of chlorophenol pesticides with overweight, obesity, lipid profile, and blood pressure in children and adolescents. Longitudinal studies are necessary to assess the clinical impact of these findings.

Urinary Metabolomics in Pediatric Obesity and NAFLD Identifies Metabolic Pathways/Metabolites Related to Dietary Habits and Gut-Liver Axis Perturbations.

To get insight into still elusive pathomechanisms of pediatric obesity and non-alcoholic fatty liver disease (NAFLD) we explored the interplay among GC-MS studied urinary metabolomic signature, gut liver axis (GLA) abnormalities, and food preferences (Kid-Med). Intestinal permeability (IP), small intestinal bacterial overgrowth (SIBO), and homeostatic model assessment-insulin resistance were investigated in forty children (mean age 9.8 years) categorized as normal weight (NW) or obese (body mass index <85th or >95th percentile, respectively) ± ultrasonographic bright liver and hypertransaminasemia (NAFLD). SIBO was increased in all obese children (p = 0.0022), IP preferentially in those with NAFLD (p = 0.0002). The partial least-square discriminant analysis of urinary metabolome correctly allocated children based on their obesity, NAFLD, visceral fat, pathological IP and SIBO. Compared to NW, obese children had (1) higher levels of glucose/1-methylhistidine, the latter more markedly in NAFLD patients; and (2) lower levels of xylitol, phenyl acetic acid and hydroquinone, the latter especially in children without NAFLD. The metabolic pathways of BCAA and/or their metabolites correlated with excess of visceral fat centimeters (leucine/oxo-valerate), and more deranged IP and SIBO (valine metabolites). Urinary metabolome analysis contributes to define a metabolic fingerprint of pediatric obesity and related NAFLD, by identifying metabolic pathways/metabolites reflecting typical obesity dietary habits and GLA perturbations.

Steroid Metabolomic Disease Signature of Nonsyndromic Childhood Obesity.

CONTEXT: The profile of urinary steroids as measured by gas chromatography-mass spectrometry defines a subject's "steroidal fingerprint." OBJECTIVE: Here, we clustered steroidal fingerprints to characterize patients with nonsyndromic childhood obesity by "steroid metabolomic signatures." HYPOTHESIS: Nonsyndromic obesity is a symptom of different diseases and conditions, some of them will have their own signature. DESIGN: A total of 31 steroid metabolites were quantified by gas chromatography-mass spectrometry, and their excretion rates were z-transformed. Using MetaboAnalyst 3.0, we divided the subjects into 5 distinctive groups by k-means clustering. Steroidal fingerprints and clinical/biochemical data of patients in each cluster were analyzed. PATIENTS: A total of 87 obese children (44 females), aged 8.5-17.9 years, were clinically characterized, and their 24-hour urine was collected. RESULTS: Cluster 1 (n = 39, 21 females) had normal steroid profile. Cluster 2 (n = 20, 11 females) showed mild, nonspecific elevation of C19 and C21 steroids, females' resistance to polycystic ovary morphology, and hirsutism. Cluster 3 (n = 7 female), with relative 21-hydroxylase insufficiency, was characterized by partial or full polycystic ovary syndrome. Cluster 4 (n = 4 males), showed markedly elevated C21 steroids and imbalance in the 11ß-hydroxysteroid dehydrogenase system, higher insulin, increased frequency of glucose/insulin index more than 0.3, γ-glutamyl transpeptidase activity, systolic blood pressure, and tendency to liver steatosis. Cluster 5 (n = 17, 5 females) had elevated dehydroepiandrosterone and 17-OH-pregnenolone metabolites, suggesting 3ß-hydroxysteroid dehydrogenase insufficiency but no clinically unique phenotype. Z-score body mass index values were not significantly different between the clusters. CONCLUSIONS: We defined a novel concept of disease-specific steroid metabolomic signature based on urinary steroidal gas chromatography-mass spectrometry. Clustering by software designed for metabolic data analysis reclassified childhood obesity into 5 groups with distinctive signatures; groups require further definition and may require cluster-specific therapeutic strategies.

24-Hour Urinary Parameters in Overweight and Obese Children with Urolithiasis.

PURPOSE: The increasing incidence of pediatric nephrolithiasis is a growing concern and its association with obesity continues to be an area of debate. We present data on urine chemistries of overweight/obese children compared to those with a normal body mass index and history of urolithiasis treated at a single institution in the United States, and assess risk factors. MATERIALS AND METHODS: We retrospectively identified 110 stone forming patients who underwent 24-hour urine collection and stratified them according to the Centers for Disease Control and Prevention definitions of overweight/obese (body mass index above 85th/95th percentile). Absolute urine collection quantities were compared between groups. Stone risk factors were analyzed according to Litholink® specified reference ranges. RESULTS: Compared to patients with low or normal body mass index, overweight and obese patients had lower body surface area adjusted citrate (242 mg/1.73 m(2) vs 315 mg/1.73 m(2), p = 0.03), lower urine phosphate (12 mg/kg vs 14 mg/kg, p = 0.04), lower urine magnesium (1.2 mg/kg vs 1.6 mg/kg, p = 0.01) and increased incidence of hypercalciuria (31% vs 11%, p = 0.02). Differences in urine citrate, phosphate and magnesium were not apparent when analyzing stone risk factors. There was no association between body mass index and urine pH. CONCLUSIONS: Overweight and obese stone forming children have decreased levels of urine citrate, phosphate and magnesium compared to patients with normal body mass index. The incidence of hypercalciuria is increased in overweight/obese patients. In contrast to findings in adults, there is no association between urine pH and body mass index.

24-h urinary sodium excretion is associated with obesity in a cross-sectional sample of Australian schoolchildren.

Emerging evidence indicates that dietary Na may be linked to obesity; however it is unclear whether this relationship is independent of energy intake (EI). The aim of this study was to assess the association between Na intake and measures of adiposity, including BMI z score, weight category and waist:height ratio (WHtR), in a sample of Australian schoolchildren. This was a cross-sectional study of schoolchildren aged 4-12 years. Na intake was assessed via one 24-h urine collection. BMI was converted to age- and sex-specific z scores, and WHtR was used to define abdominal obesity. In children aged ≥8 years, EI was determined via one 24-h dietary recall. Of the 666 children with valid urine samples 55 % were male (average age 9·3 (sd 1·8) years). In adjusted models an additional 17 mmol/d of Na was associated with a 0·10 higher BMI z score (95 % CI 0·07, 0·13), a 23 % (OR 1·23; 95 % CI 1·16, 1·31) greater risk of being overweight/obese and a 15 % (OR 1·15; 95 % CI 1·09, 1·23) greater risk of being centrally obese. In the subsample of 8-12-year-old children (n 458), adjustment for EI did not markedly alter the associations between Na and adiposity outcomes. Using a robust measure of daily Na intake we found a positive association between Na intake and obesity risk in Australian schoolchildren, which could not be explained by total energy consumption. To determine whether this is a causal relationship, longitudinal studies, with high-quality measures of Na and EI, are required.

Urinary fibrogenic cytokines ET-1 and TGF-ß1 are associated with urinary angiotensinogen levels in obese children.

BACKGROUND: Fibrogenic cytokines are recognized as putative drivers of disease activity and histopathological deterioration in various kidney diseases. We compared urinary transforming growth factor ß1 (U-TGF-ß1) and endothelin 1 (U-ET-1) levels across body mass index classes and assessed their association with the level of urinary angiotensinogen (U-AGT), a biomarker of intrarenal renin-angiotensin-aldosterone system (RAAS). METHODS: The was a cross-sectional evaluation of 302 children aged 8-9 years. Ambulatory blood pressure (BP), insulin resistance (HOMA-IR), aldosterone level and renal function were evaluated. U-ET-1, U-TGF-ß1 and U-AGT levels were determined by immunoenzymatic methods. RESULTS: Obese children presented with the lowest levels of U-ET-1 and U-TGF-ß1, but the difference was only significant for U-ET-1. In obese children, the median levels of both U-ET-1 and U-TGF-ß1 tended to increase across tertiles (T1-T3) of U-AGT (U-ET-1: T1, 19.9 (14.2-26.3); T2, 32.5 (23.3-141.6); T3, 24.8 (18.7-51.5) ng/g creatinine, p = 0.007; U-TGF-ß1: T1, 2.2 (1.8-4.0); T2, 4.3 (2.7-11.7); T3, 4.9 (3.8-10.1) ng/g creatinine, p = 0.004]. In multivariate models, in the obese group, U-ET-1 was associated with HOMA-IR and aldosterone and U-AGT levels, and U-TGF-ß1 was associated with U-AGT levels and 24 h-systolic BP. CONCLUSIONS: Whereas the initial hypothesis of higher levels of urinary fibrogenic cytokines in obese children was not confirmed in our study, both TGF-ß1 and U-ET-1 levels were associated with U-AGT level, which likely reflects an early interplay between tissue remodeling and RAAS in obesity-related kidney injury.

Total body water measurement using the 2H dilution technique for the assessment of body composition of Kuwaiti children.

OBJECTIVE: The 2H dilution technique is the reference method to estimate total body water for body composition assessment. The aims of the present study were to establish the total body water technique at the Kuwait Institute for Scientific Research and assess body composition of Kuwaiti children. DESIGN: The isotope ratio mass spectrometer was calibrated with defined international reference water standards. A non-random sampling approach was used to recruit a convenience sample of Kuwaiti children. A dose of 2H2O, 1-3 g, was consumed after an overnight fast and 2H enrichment in baseline and post-dose urine samples was measured. Total body water was calculated and used to estimate fat-free mass. Fat mass was estimated as body weight minus fat-free mass. SETTING: The total body water study was implemented in primary schools. SUBJECTS: Seventy-five boys and eighty-three girls (7-9 years). RESULTS: Measurements of the isotope ratio mass spectrometer were confirmed to be accurate and precise. Children were classified as normal weight, overweight or obese according to the WHO based on BMI-for-age Z-scores. Normal-weight and overweight girls had significantly higher percentage body fat (median (range): 32·4 % (24·7-39·3 %) and 38·3 % (29·3-44·2 %), respectively) compared with boys (median (range): 26·5 % (14·2-37·1 %) and 34·6 % (29·9-40·2 %), respectively). No gender difference was found in obese children (median 46·5 % v. 45·6 %). CONCLUSIONS: The establishment of a state-of-the-art stable isotope laboratory for assessment of body composition provides an opportunity to explore a wide range of applications to better understand the relationship between body size, body composition and risk of developing non-communicable diseases in Kuwait.

The effects of phthalate and nonylphenol exposure on body size and secondary sexual characteristics during puberty.

BACKGROUND: Some phthalic acid esters (PAEs) and nonylphenol (NP) are endocrine-disrupting chemicals (EDCs) that are widely used in consumer products. Consequently, the general population is exposed simultaneously to both groups of chemicals. OBJECTIVE: To investigate the single- and co-exposure effects of PAEs (DMP, DEP, DnBP, DiBP, BBzP, and DEHP) and NP on obesity and pubertal maturity to compare the body sizes of general adolescents with the complainants of the phthalate-tainted foods scandal that occurred in Taiwan. METHODS: This study included 270 general adolescents aged 6.5-15.0 years and 38 complainants aged 6.5-8.5 years. Nine metabolites of the five PAEs and of NP were measured in urine. We used a questionnaire to evaluate pubertal maturity, measured anthropometric indices (APs) to assess body size, and collected urine samples to measure the two groups of chemicals. RESULTS: We found that urinary PAE metabolite concentrations (specifically, metabolites of DEP, DnBP, DiBP, and DEHP) were positively associated with the APs for abdominal obesity (including skinfold thickness, waist circumference, waist-to-height ratio, and waist-to-hip) and indicated a dose-response relationship. Mono-methyl phthalate (MMP) exposure was inversely associated with pubarche among boys. The daily intake of DEHP in general adolescents exceeded the reference doses (RfD-20 µg/kgbw/day) and tolerable daily intake (TDI-50 µg/kgbw/day) by 3.4% and 0.4%, respectively. No associations were observed between NP exposure or co-exposure and the APs or pubertal maturity. No significant differences were observed between general adolescents and the complainants with regard to weight, height, or BMI. CONCLUSIONS: The study suggests that PAE (specifically, DEP, DnBP, DiBP, and DEHP) exposure is associated with abdominal obesity in adolescents and that the APs for abdominal obesity are more sensitive than BMI for measuring obesity among adolescents. We suggest that the RfD and TDI for PAEs should be revised to provide sufficient protection.