Factors associated with insulin resistance and non-alcoholic fatty liver disease among youths

Visceral Adiposity, Anthropometric and Liver Function Indexes for Identifying Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD) in Adolescents with Obesity: Which Performs Better?

Background: Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD) is the accumulation of fat in the liver without excessive alcohol consumption or other known liver diseases. MASLD is the most common liver disease in adolescents with obesity. The aims of this study were as follows: (i) to determine which index (waist circumference BMI, WHtR, VAI, METS-IR, METS-VF, HSI, FLI, or MetS_zscore) best explains the prevalence of MASLD in adolescents with obesity; (ii) to determine whether there was a specific index that was most strongly associated with MASLD; (iii) to assess which liver function indexes were most strongly correlated with MASLD. Methods: A total of 758 adolescents with severe obesity (BMI z-score > 2) admitted at the Division of Auxology, Istituto Auxologico Italiano, IRCCS, Piancavallo-Verbania for a 3-week multidisciplinary body weight reduction program were selected. Anthropometric parameters (stature, body mass, BMI, and waist and hip circumference) were collected, and body composition (lean and fat mass) was determined using the tetrapolar bioimpedance analysis (BIA) technique. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (gamma GT), alkaline phosphatase (ALP), bilirubin, glucose, total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), triglycerides (TG), and C-reactive protein (CRP) were measured using standard techniques. MASLD was diagnosed based on abdominal ultrasound results. Results: WHtR (65.76%) was the most sensitive compared with other indexes. The HSI (AUC: 0.67 (0.63-0.71, 95% CI), p-value < 0.05) showed the best performance in predicting MASLD, with the threshold for having MASLD considered at 48.22. The indexes that showed the worst performance in predicting MASLD were the MetS z-score (AUC: 0.56 (0.52-0.60)) and the VAI (AUC: 0.57 (0.52-0.61)). ALT (OR: 2.92 (2.29-3.77); 95% CI) and AST (OR: 2.52 (2.03-3.20)) were the parameters with a stronger correlation with MASLD. Conclusions: The most sensitive index for diagnosing MASLD was the WHtR, based exclusively on anthropometric parameters. HSI was the index that correlated the most with MASLD, while the parameters of liver function (ALT and AST) were the most strongly correlated with the disease and its severity.

Oxidized high-density lipoprotein and low-density lipoprotein in adolescents with obesity and metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is increasingly common in the pediatric population and may increase risk for developing cardiovascular disease (CVD) in people with MASLD. Oxidized high-density lipoprotein (oxHDL) and oxidized low-density lipoprotein (oxLDL) are modified, pro-atherosclerotic lipoproteins that are increased in adults with MASLD and CVD but have not been reported in adolescents with MASLD.

PURPOSE

To determine if oxLDL and oxHDL are increased in adolescents with MASLD.

METHODS

Fasting oxHDL and oxLDL were measured in adolescents (11-20 years) with obesity and biopsy-confirmed MASLD (n = 47), and peers without MASLD but with obesity (Ob; n = 28), or normal weight (NW; n = 29).

RESULTS

oxHDL was 27% higher (p < 0.05) in the MASLD group (mean ± SD: 11.9 ± 4.7 ng/mL) compared to the Ob group (9.3 ± 3.7 ng/mL, p < 0.05) but only 7% higher than the NW group (11.1 ± 3.8 ng/mL, p > 0.05). However, HDL-C was 19% and 32% lower in the MASLD group than in the Ob and NW groups, respectively. Thus, oxHDL/HDL-C ratio was 55% and 66% higher in MASLD compared to the Ob group (p < 0.004) and the NW group (p < 0.001), respectively. oxLDL (52.4 ± 16.0, 46.7 ± 10.1 and 47.1 ± 15.2 U/L for MASLD, Ob and NW, respectively), LDL-C and the oxLDL/LDL-C ratio did not differ among groups.

CONCLUSIONS

The elevated oxHDL and oxHDL/HDL-C in adolescents with MASLD compared to peers with Ob or NW suggests that there is some oxidative stress in MASLD independent of obesity and potential for increased CVD risk in the future.

Insulin resistance-related circulating predictive markers in the metabolic syndrome: a systematic review in the Iranian population

Background

Specific biomarkers for metabolic syndrome (MetS) may improve diagnostic specificity for clinical information. One of the main pathophysiological mechanisms of MetS is insulin resistance (IR). This systematic review aimed to summarize IR-related biomarkers that predict MetS and have been investigated in Iranian populations.

Methods

An electronic literature search was done using the PubMed and Scopus databases up to June 2022. The risk of bias was assessed for the selected articles using the instrument suggested by the Joanna Briggs Institute (JBI). This systematic review protocol was registered with PROSPERO (registration number CRD42022372415).

Results

Among the reviewed articles, 46 studies investigated the association between IR biomarkers and MetS in the Iranian population. The selected studies were published between 2009 and 2022, with the majority being conducted on adults and seven on children and adolescents. The adult treatment panel III (ATP III) was the most commonly used criteria to define MetS. At least four studies were conducted for each IR biomarker, with LDL-C being the most frequently evaluated biomarker. Some studies have assessed the diagnostic potency of markers using the area under the curve (AUC) with sensitivity, specificity, and an optimal cut-off value. Among the reported values, lipid ratios and the difference between non-HDL-C and LDL-C levels showed the highest AUCs (≥ 0.80) for predicting MetS.

Conclusions

Considering the findings of the reviewed studies, fasting insulin, HOMA-IR, leptin, HbA1c, and visfatin levels were positively associated with MetS, whereas adiponectin and ghrelin levels were negatively correlated with this syndrome. Among the investigated IR biomarkers, the association between adiponectin levels and components of MetS was well established.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01347-6.

Cardiorespiratory and Muscular Fitness in Children and Adolescents with Obesity

PURPOSE OF REVIEW

Examine the current state of literature related to the impact of obesity in children and adolescents on health-related physical fitness and the resultant cardiometabolic disease risk.

RECENT FINDINGS

Cardiorespiratory fitness of children and adolescents has declined over the past few decades which corresponds with an increase in obesity rates. Children with obesity are more likely to have low cardiorespiratory fitness which is associated with higher cardiometabolic disease risk and poorer mental health. The impact of obesity on muscular fitness in children and adolescents is more difficult to ascertain, but in general measures of physical function are lower in children with obesity which has also been associated with higher cardiometabolic disease risk. Components of health-related physical fitness are trending negatively in children and adolescents and appear to be related to the increase in prevalence of obesity. The resultant cardiometabolic disease risk has also risen which suggests a greater disease burden in the future. These disparaging findings highlight the need for aggressive interventions to improve physical fitness in children and adolescents.

Adiponectin is Inversely Associated with Insulin Resistance in Adolescents with Nonalcoholic Fatty Liver Disease

BACKGROUND

Insulin resistance(IR) is confirmed as a key feature of nonalcoholic fatty liver disease (NAFLD) in children and adolescents. Numerous studies report that adiponectin (APN) levels are inversely associated with the status of IR in adults with NAFLD. This study aimed to investigate the relationship between serum total APNand homeostasis model assessment insulin resistance(HOMA-IR) in adolescents with NAFLD.

METHODS

382 newly-diagnosed NAFLD adolescents, aged 9-16 years old, were enrolled and divided into 3 subgroups according to the APNtertile. Simple and multiple linear regression analyses were performed to assess the correlation between HOMA-IR and APN in boys and girls, respectively.

RESULTS

The HOMA-IR values tended to decrease in boys according to APN tertiles: 5.6(4.4-7.3) vs. 5.2(4.6-6.9) vs. 4.9(4.1-5.8) (P<0.01), and there was a significant difference in the HOMA-IR values among three APN tertile subgroups in girls(P<0.01).Univariate analysis showed thatbody mass index, waist circumference, weight-to-height ratio, fasting blood glucose, insulin, triglyceride, and APN were significantly associated with HOMA-IR in boys (P<0.05). In girls, body mass index, fasting blood glucose, insulin, total cholesterol, triglyceride, and APN were significantly associated with HOMA-IR (P<0.05).APN was found to be a significant determinant for HOMA-IR only in boys (β=-0.147, P<0.01).

CONCLUSION

Our findings showed that APN was an independent and significant determinant for increased HOMA-IR in boys with NAFLD. Further studies are needed to explore the underlying mechanisms.

Changes in Liver Enzymes and Metabolic Profile in Adolescents with Fatty Liver following Exercise Interventions

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is the most frequent cause of chronic liver diseases in both adults and children with obesity. The aim of this study was to compare the changes in liver enzymes and metabolic profile in adolescents with fatty liver following selected school-based exercise (SBE) and high-intensity interval training (HIIT) interventions.

METHODS

In a semi-experimental study, 34 obese male adolescents with clinically defined NAFLD were divided into the HIIT (n=11, age=12.81±1.02 years, body mass index [BMI]=26.68 ±2.32 kg/m²), selected SBE (n=11, age=13.39±0.95 years, BMI=26.47±1.74 kg/m²), and control (n=12, age=13.14±1.49 years, BMI=26.45±2.21 kg/m²) groups. The ultrasonography NAFLD grade, peak oxygen uptake (VO_2peak), lipid profile, insulin resistance, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels of the participants were measured before and after the exercise interventions.

RESULTS

The BMI, waist-to-hip ratio, and body fat percentage of the participants decreased, and a significant increase in VO_2peak was observed after the intervention; however, the HIIT group showed a significant improvement compared with the SBE group (p<0.01). Significant reductions were observed in the levels of insulin resistance, triglyceride, total cholesterol, ALT, and AST in both groups, although high-density lipoprotein levels decreased only in the HIIT group (p<0.01). Further, a significant reduction in low-density lipoprotein level was observed in the training groups (p<0.01), but this decrease was not significant compared with the control group (p>0.01).

CONCLUSION

HIIT and SBE are equally effective in improving health parameters in obese children and adolescents.

Cardiorespiratory Fitness in Youth: An Important Marker of Health: A Scientific Statement From the American Heart Association

Cardiorespiratory fitness (CRF) refers to the capacity of the circulatory and respiratory systems to supply oxygen to skeletal muscle mitochondria for energy production needed during physical activity. CRF is an important marker of physical and mental health and academic achievement in youth. However, only 40% of US youth are currently believed to have healthy CRF. In this statement, we review the physiological principles that determine CRF, the tools that are available to assess CRF, the modifiable and nonmodifiable factors influencing CRF, the association of CRF with markers of health in otherwise healthy youth, and the temporal trends in CRF both in the United States and internationally. Development of a cost-effective CRF measurement process that could readily be incorporated into office visits and in field settings to screen all youth periodically could help identify those at increased risk.

Association of Socioeconomic Status and Food Security with Anthropometric Indices Among 2-5-year-old Urban Children in Eight Different cities in Iran

Introduction:

Child nutrition status is very important in all societies, which is influenced by the interaction of multiple factors including food security and socioeconomic status in both genders. The aim of this study was to examine the relationship between food security and socioeconomic status with anthropometric indices among 2–5-year-old urban children in eight different cities in Iran.

Materials and Methods:

In this cross-sectional study, anthropometric Z scores of 7028 children of urban area were measured by using World Health Organization (WHO) Anthro software based on WHO 2007 standards. Family food security was assessed by using HFIAS 9-item questionnaire. Socioeconomic status as well as health factors were analyzed using the SPSS.

Results:

Based on the present study, significant correlation was observed between sleep time, birth weight, and food security (P < 0.05) with body mass index (BMI), while the rest of the variables including age, family size, number of children, parents’ education, breastfeeding duration, watching TV, playing computer games, playing outdoors, number of main eating, and number of snacks showed no significant relation (P > 0.05).

Conclusion:

It was shown that 2–5 years old children's life are the most vital and vulnerable to the hazards of undernutrition or overweight and obesity, which could affect the whole health of the person. As food security affects BMI, it is important to focus more on this issue in order to improve child's health status.

Association of carotid intima media thickness with atherogenic index of plasma, apo B/apo A-I ratio and paraoxonase activity in patients with non-alcoholic fatty liver disease

BACKGROUND

NAFLD patients have higher risk of atherosclerosis cardiovascular disease (ASCVD). apo B/apoA-I ratio and atherogenic index of plasma (AIP) have been suggested as biomarker for ASCVD.

METHODS

apo A-I, apoB, aryl esterase (ARE) and paraoxonase (PON) activities and carotid intima media thickness (cIMT) were determined in 49 NAFLD patients and 33 controls.

RESULTS

Plasma levels of apo A-I, adiponectin, ARE and PON activities decreased in NAFLD patients, while apo B, AIP and apoB/apo A-I ratio level were higher in NAFLD patients compared to controls. Furthermore, cIMT showed a positive association with AIP, apo B/apo A-I ratio and AIP + (apo B/apo A-I) in NAFLD patients. Strikingly, AIP + (apo B/apo A-I) showed a good ability to discriminating increased cIMT in NAFLD patients.

CONCLUSIONS

The result showed that AIP and apo B/apo A-I associated with cIMT in NAFLD patients; however, more study are needed to prove this concept.

Is There an Association of Vascular Disease and Atherosclerosis in Children and Adolescents With Obesity and Non-alcoholic Fatty Liver Disease?

Carotid intima media thickness (cIMT) and brachial flow-mediated dilation (FMD) evaluated by ultrasound are non-invasive markers of atherosclerosis. Increased cIMT in adults has been correlated to early vascular damage. Several studies show similar correlations of elevated cIMT in children with obesity, hyperlipidemia, and metabolic syndrome. Additionally, several articles have correlated non-alcoholic fatty liver disease (NAFLD) with elevated cIMT, indicating early atherosclerosis. It is alarming that these vascular changes may be seen in children as young as 10 years of age. Children with NAFLD may also have an increased pulse wave velocity that correlates to increased arterial stiffness and increased left ventricular dimension, mass, and diastolic dysfunction. These articles are persuasive, indicating a correlation of Pediatric NAFLD and early vascular disease. However, study limitations include the use of elevated alanine aminotransferase (ALT) and echogenic changes on ultrasound that may have low accuracy to identify NAFLD. Ultrasound has low sensitivities and specificities for detection of NAFLD and therefore is not recommended for diagnosis. In comparison, studies that used liver biopsy or proton magnetic resonance spectroscopy to identify NAFLD did not find a correlation with elevated cIMT or reduction in FMD. Due to these conflicting findings, more studies looking at cIMT and FMD changes in children with NAFLD are needed with more accurate diagnostic methods for steatosis to identify if there truly is a correlation of increased liver steatosis to early atherosclerosis.

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.

Insulin resistance and the metabolic syndrome are related to the severity of steatosis in the pediatric population with obesity

BACKGROUND

To determine the factors associated with an increased risk for severe steatosis (SS) and establish the Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) as a screening tool.

METHODS

A cross-sectional study was performed in obese children to assess the relationship between the metabolic syndrome (MetS) and glucose metabolism alterations (GMA) and the risk for severe steatosis.

RESULTS

A total of 94 children (51 males) aged from six to 14 years were included. Thirteen children (14.8%) had severe steatosis (SS). The anthropometric variables associated with SS included body mass index (BMI) (SS 34.1 vs non-SS 29.7, p = 0.005), waist circumference (cm) (100 vs 92.5, p = 0.015) and hip circumference (cm) (108 vs 100, p = 0.018). The blood parameters included alanine aminotransferase (ALT) (UI/dl) (27 vs 21, p = 0.002), gamma-glutamil transpeptidase (GGT) (UI/dl) (16 vs 15, p = 0.017), fasting glycemia (mg/dl) (96 vs 88, p = 0.006), fasting insulin (UI/dl) (25 vs 15.3, p < 0.001) and HOMA-IR score (7.1 vs 3.7, p < 0.001). Eighteen children with MetS were found to be at an increased risk for severe steatosis (odds ratio [OR] 11.36, p < 0.001). After receiver operating characteristic (ROC) curve analysis, the best area under the curve (AUC) was obtained for HOMA-R of 0.862. The HOMA-R 4.9 cut-off value had a 100% sensitivity (CI 95%: 96.2-100) and 67.9% specificity (CI 95%: 57.1-78.7) for severe steatosis.

CONCLUSIONS

The presence of MetS and glucose metabolism alterations are risk factors for severe steatosis. The 4.9 cut-off value for HOMA-IR may be a risk factor for severe steatosis in obese children.

The Association between Non-Alcoholic Fatty Liver Disease and Cardiovascular Risk in Children

The rising prevalence of childhood obesity in the past decades has made Non-Alcoholic Fatty Liver Disease (NAFLD) the most common cause of pediatric chronic liver disease worldwide. Currently, a growing body of evidence links NAFLD with cardiovascular disease (CVD) even at an early age. Data on the pediatric population have shown that NAFLD could represent an independent risk factor not only for cardiovascular events but also for early subclinical abnormalities in myocardial structure and function. Briefly, we review the current knowledge regarding the relationship between pediatric NAFLD and cardiovascular risk in an attempt to clarify our understanding of NAFLD as a possible cardiovascular risk factor in childhood.

Ideal cardiovascular health and liver enzyme levels in European adolescents; the HELENA study

There is an increasing interest for the role of liver enzymes as predictors of non-liver-related morbidity and mortality. The American Heart Association (AHA) described the ideal cardiovascular health concept as a score of seven cardiovascular health behaviors and factors that can be used to monitor and predict ideal cardiovascular health over time. This study aimed to examine the association of the ideal cardiovascular health (ICH), as defined by the AHA, with liver enzyme levels in European adolescents. A total of 637 adolescents (54.6% females), aged 14.6 ± 1.2 years from nine European countries participated in this cross-sectional study. Blood levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase were measured and the AST/ALT ratio calculated. Ideal cardiovascular health was defined as meeting ideal levels of the following components: four behaviors (smoking, body mass index, physical activity, and diet) and three factors (total cholesterol, blood pressure, and glucose). A higher number of ideal cardiovascular health behaviors, factors, and ideal cardiovascular health index were associated with lower ALT (P < 0.05, P < 0.001, and P < 0.001, respectively) and gamma-glutamyltransferase (P < 0.001, P < 0.01, and P < 0.001, respectively) levels. Similarly, a higher number of ideal cardiovascular health behaviors (P < 0.01), factors (P < 0.01), and ideal cardiovascular health index (P < 0.001) were associated with a higher aspartate aminotransferase to alanine aminotransferase ratio. These findings reinforce the usefulness of the ICH index as an instrument to identify target individuals and promote cardiovascular health in adolescents, and it also extends these observations to the liver manifestation of the metabolic syndrome.

Cardiorespiratory fitness, waist circumference and liver enzyme levels in European adolescents: The HELENA cross-sectional study

OBJECTIVES

(1) To examine whether cardiorespiratory fitness (CRF) is related to liver enzyme levels independent of waist circumference (WC), and (2) To test whether having a high CRF is associated with an improved liver enzyme profile with a high WC.

DESIGN

Cross-sectional.

METHODS

CRF (20m-shuttle-run test) and WC were assessed in 811 European adolescents (48.5% males) aged 12.5-17.5 years. Fatty liver biomarkers included fasting serum alanine-aminotransferase (ALT), gamma-glutamyl-transpeptidase (GGT) and the aspartate-aminotransferase to ALT (AST/ALT) ratio. Participants were categorized as fit or unfit (CRF below or above 43.8mL/kg/min and 34.6mL/kg/min, for boys and girls, respectively) and as high or non-high WC (sex and age-specific cut-offs).

RESULTS

CRF was associated with ALT (β=-0.106; p=0.049) and GGT levels (β=-0.225; p<0.001) and AST/ALT ratio (β=0.234; p<0.001), yet these relationships were attenuated after further controlling for WC (all p>0.1). High WC and fit adolescents had lower ALT levels (28±1U/L vs. 23±2U/L, unfit and fit respectively, p=0.018) and higher AST/ALT ratio (0.94±0.04 vs. 1.10±0.06, unfit and fit respectively, p=0.010) than those who were high WC but unfit.

CONCLUSIONS

The results showed that CRF is not independently associated with liver enzymes, and that WC is a stronger predictor in adolescents. These findings also suggest that high CRF may have specific protective effects on liver enzyme levels in adolescents with high WC. Exercise programs focused on increasing CRF and decreasing abdominal adiposity could be a good alternative in the treatment and prevention of obesity related fatty liver disease in adolescents.

Obesity-related insulin resistance in adolescents: a systematic review and meta-analysis of observational studies

Insulin resistance is common among obese adolescents; however, the extent of this problem is not clear. We conducted a systematic review of PubMed-Medline, CINAHL, The Web of Science, EMBASE and Scopus for observational studies evaluating components defining insulin resistance (insulin, C-peptide and homeostatic model assessment-insulin resistance [HOMA-IR]) in obese adolescents (12-18 years) versus non-obese adolescents. Our systematic review and meta-analysis followed the PRISMA guidelines. Data were combined using a random-effects model and summary statistics were calculated using the mean differences (MDs). 31 studies were included (n = 8655). In 26 studies, fasting insulin levels were higher in obese adolescents when compared to non-obese adolescents (MD = 64.11 pmol/L, 95%CI 49.48-78.75, p < 0.00001). In three studies, fasting C-peptide levels were higher in obese adolescents when compared to non-obese adolescents (MD = 0.29 nmol/L, 95%CI 0.22-0.36, p < 0.00001). In 24 studies, HOMA-IR values were higher in obese adolescents when compared to non-obese adolescents (MD = 2.22, 95%CI 1.78-2.67, p < 0.00001). Heterogeneity of effects among studies was moderate to high. Subgroup analyses showed similar results to the main analyses. Circulating insulin and C-peptide levels and HOMA-IR values were significantly higher in obese adolescents compared to those non-obese.

Comparing the role of standard references on the prevalence of Iranian children and adolescents' overweight and obesity: A systematic review and meta-analysis

Background:

Obesity is a major risk factor for chronic diseases and has a role on high blood pressure, diabetes type II, etc., This review assesses the prevalence of Iranian children obesity and overweight for different age categories and compares the three standard definitions of obesity.

Materials and Methods:

To retrieve desirable studies concerning childhood anthropometric data from different area of Iran, the MEDLINE, Scopus, and different local databases such as Scientific Information database were used. The studies reported the prevalence of obesity or overweight of children < 6, 6–12, and 12–20 years old, despite differences between definitions of childhood obesity, were included in the study. We combined the reported prevalence of the overweight and obesity with regard to age and gender, and also by the different standard references which are the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO) definition, and the International Obesity Task Force (IOTF) references. The analysis was carried out using STATA software.

Results:

Our review covered 75 articles reported the prevalence of overweight or obesity among children and adolescents for different age groups in Iran. Our meta-regression analysis showed that the prevalence of obesity and overweight did not vary significantly in gender and age categories, but different definitions provide different prevalence of overweight and obesity.

Conclusion:

The effective factors on obesity and overweight included administration policy and organizational, interpersonal, intrapersonal, and social factors. CDC and WHO references intended in monitoring children's growth and the IOTF cutoffs would rather provide a common set of definitions that researchers and policymakers could use for descriptive and comparative purposes.

Relation of insulin resistance with social-demographics, adiposity and behavioral factors in non-diabetic adult Canadians

BACKGROUND

Insulin resistance is a pathogenic factor for type II diabetes and has been associated with metabolic abnormalities and adverse clinical outcomes. The purpose of this study was to examine the relationship between insulin resistance and socio-demographics, adiposity and behavioral factors in the general, non-diabetic adult Canadian population.

METHODS

Data for 3515 non-diabetic adults aged 18 to 79 years from the Canadian Health Measures Survey (cycles 1 and 2, 2007-2011) were analyzed. Insulin resistance index was measured by the homeostasis model assessment of insulin resistance (HOMA-IR), and insulin resistance (IR) was defined as individuals in the highest quartile of the HOMA-IR index. Logistic regression models were used to examine the effect of demographics, lifestyle factors and adiposity measurements on HOMA-IR.

RESULTS

The risk of IR increased with age, particularly in men. Individuals had adjusted odds ratio (OR) (with corresponding 95 % confidence interval) of 5.97 (2.90-8.52) and 25.12 (15.20-41.51) associated with a body-mass-index (BMI) between 25.0 and < 30.0, or ≥30.0, of 9.23 (6.52-13.07) with abdominal obesity (waist circumstance ≥102 cm for men and ≥ 88 cm for women), of 8.72 (6.13-12.39) with a high waist-to-height ratio (>0.57), and of 6.30 (4.33-9.16) with a high waist-to-hip ratio (>0.90 for men and >0.85 for women). Physically inactive people and non-alcohol consumer also had a significantly higher odd of IR.

CONCLUSIONS

This study found that men and older, obese and physically inactive people were at increased risk for IR. Adiposity indices including BMI, waist circumstance, waist-to-height ratio and waist-to-hip ratio were highly associated with IR with similar magnitude of association.

Portal inflammation is independently associated with fibrosis and metabolic syndrome in pediatric nonalcoholic fatty liver disease

Pediatric nonalcoholic fatty liver disease (NAFLD) histology demonstrates variable amounts of portal inflammation, which may be associated with more severe liver disease and fibrosis. We assessed the relationship between portal inflammation, hepatic fibrosis, and the metabolic syndrome in pediatric NAFLD. Children with biopsy-proven NAFLD were eligible for inclusion. Histology was assessed using Kleiner fibrosis stage and the Nonalcoholic Steatohepatitis Clinical Research Network system for portal inflammation. Patients were divided by histology into type 1, type 2, and overlap NAFLD. Multivariable ordinal logistic regression was used to determine factors associated with fibrosis and portal inflammation. The 430 Caucasian children were divided into 52 with type 1, 95 with type 2, and 283 with overlap NAFLD. Those with type 2 had a more severe metabolic phenotype, with higher body mass index z score (2.0 versus 1.6, P < 0.0001), waist circumference centile (96th versus 90th, P < 0.0001), and triglycerides (84 versus 77 mg/dL, P = 0.01) and lower high-density lipoprotein (46 versus 60 mg/dL, P = 0.004) than those with type 1. Similarly, those with overlap NAFLD had a more severe phenotype. Stage 2-3 fibrosis was present in 69/283 (24%) with overlap NAFLD. Portal inflammation was associated with stage 2-3 fibrosis on multivariable analysis (95% confidence interval 1.4-5.2, odds ratio = 3.7). Waist circumference centile was associated with portal inflammation (95% confidence interval 1.2-3.4, odds ratio = 2.0).

CONCLUSION

Portal inflammation is associated with more advanced pediatric NAFLD and features of the metabolic syndrome.

Physical Activity Is Prospectively Associated With Adolescent Nonalcoholic Fatty Liver Disease

OBJECTIVES

The aim of the present study was to assess whether objectively measured physical activity at mean ages 12 and 14 years are prospectively associated with ultrasound scan liver fat and stiffness (alanine aminotransferase, aspartate aminotransferase [AST], and γ-glutamyl transferase [GGT]) assessed at mean age 17.8 years.

METHODS

Participants were from the Avon Longitudinal Study of Parents and Children. Total physical activity (counts per minute) and minutes of moderate to vigorous physical activity (MVPA) were measured using ActiGraph accelerometers at mean ages 12 and 14 years.

RESULTS

Greater total physical activity and MVPA at ages 12 and 14 years were associated with lower odds of liver fat and lower GGT levels at mean age 17.8 years, such as per 15-minute increase in daily MVPA at age 12 years, the confounder adjusted odds ratio of liver fat was 0.47 (95% confidence interval [CI] 0.27-0.84). Associations attenuated after additional adjustment for fat mass as a potential confounder (eg, per 15-minute increase in daily MVPA at age 12 years, the odds ratio of liver fat attenuated to 0.65 [95% CI 0.35-1.21]) or a potential mediator (eg, per 15-minute increase in daily MVPA at age 12 years the odds ratio of liver fat attenuated to 0.59 [95% CI 0.32-1.09]). Results did not further attenuate after additional adjustment for insulin resistance. There was some evidence that greater total physical activity and MVPA at age 12 years were associated with the higher AST levels.

CONCLUSIONS

Adolescents who were more active in childhood have lower odds of fatty liver and lower GGT levels. These findings are likely to be, at least in part, explained by adiposity.

Liver enzymes and clustering cardiometabolic risk factors in European adolescents: the HELENA study

OBJECTIVES

This study aimed to explore the associations of liver biomarkers with cardiometabolic risk factors and their clustering, and to provide reference values (percentiles) and cut-off points for liver biomarkers associated with high cardiometabolic risk in European adolescents.

METHODS

Alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), aspartate aminotransferase to ALT ratio (AST/ALT), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol and insulin were measured in 1084 adolescents. We computed a continuous cardiometabolic risk score and defined the high cardiometabolic risk.

RESULTS

Higher ALT and GGT and lower AST/ALT were associated with adiposity and with the number of adverse cardiometabolic risk factors (Ps < 0.05). Higher GGT and lower AST/ALT were associated with higher cardiometabolic risk score (Ps < 0.001) in males and females, and ALT only in males (Ps < 0.001). Gender- and age-specific percentiles for liver biomarkers were provided. Receiver operating characteristic analyses showed a significant discriminatory accuracy of AST/ALT in identifying the low/high cardiometabolic risk (Ps < 0.01) and thresholds were provided.

CONCLUSIONS

Higher GGT and lower AST/ALT are associated with higher cardiometabolic risk factors and their clustering in male and female European adolescents, whereas the associations of ALT were gender dependent. Our results suggest the usefulness of AST/ALT as a screening test in the assessment of adolescents with high cardiometabolic risk and provide gender- and age-specific thresholds that might be of clinical interest.

Nonalcoholic fatty liver disease and cardiovascular risk in children with obesity

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) has been recognized as an independent risk factor for cardiovascular disease in adults. It has not been established whether NAFLD is related to early atherosclerotic changes in children.

METHODS

In a cross-sectional study, 78 non diabetic, non smoking children with severe obesity were evaluated for NAFLD. Proton magnetic resonance spectroscopy was used to detect liver steatosis and serum ALT was used as a surrogate marker for steatohepatitis. Carotid intima-media thickness (CIMT) and arterial wall stiffness were measured using ultrasound.

RESULTS

Steatosis was present in 41 (53%) of subjects. Of these children, 26 out of 41 (63%) had elevated ALT levels. No differences in CIMT and arterial wall stiffness were observed between those without and with steatosis and those with steatosis plus elevated ALT levels [CIMT = 0.47 (±0.06), 0.48 (±0.06) and 0.48 (±0.07) mm, respectively; stiffness = 2.78 (±0.50), 3.00 (±0.81), and 2.90 (±0.78), respectively]. Steatosis and ALT were not correlated to CIMT (r = -0.02 and -0.14, respectively) or arterial wall stiffness (r = 0.13 and -0.11, respectively).

CONCLUSIONS

In this study, no relationship between NAFLD and early atherosclerotic changes in children was observed. An atherogenic effect of steatohepatitis (NASH) on pediatric age and long-term atherogenic consequences of simple steatosis cannot be excluded based on this study.

Risk factors for non-alcoholic fatty liver disease combined with type 2 diabetes mellitus in adolescents

AIM: To investigate the risk factors for non-alcoholic fatty liver disease (NAFLD) combined with type 2 diabetes mellitus (T2DM) in adolescents.

METHODS: A long-term follow-up study of 721 urban adolescents showed that there were 134 NAFLD cases and 17 cases of T2DM. Twelve NAFLD patients had combined T2DM. The risk factors for NAFLD combined with T2DM were analyzed using univariate and multivariate logistic regression analyses.

RESULTS: The NAFLD prevalence rate in urban adolescents was 18.6%. The prevalence rate in males was significantly higher than that in females (P < 0.05). The percentage of patients with a fatty liver family history, body mass index (BMI), waist-hip ratio (WHR), ratio of intra-abdominal obesity, 2 h postprandial blood glucose (2 h PBG) and rate of T2DM in NAFLD patients were significantly higher than those in non-NAFLD patients (P < 0.05). BMI, WHR, severity of fatty liver, fasting blood glucose (FBG), aspartate aminotransferase (AST), gamma glutamine transferase (γ-GT), total cholesterol (TC), and the percentages of patients with diabetes family history or fatty liver family history in NAFLD patients with T2DM were significantly higher than those in NAFLD patients without T2DM (P < 0.05). Univariate logistic regression analysis showed that age, BMI ≥ 28 kg/m², intra-abdominal obesity, fatty liver family history and diabetes family history were significantly related to NAFLD combined with T2DM. In the following multivariate logistic regression, only BMI ≥ 28 kg/m² and diabetes family history were significantly related to NAFLD combined with T2DM in adolescents.

CONCLUSION: The rate of T2DM in NAFLD adolescents is significantly higher than that in non-NAFLD adolescents. Obesity (BMI ≥ 28 kg/m²) and diabetes family history are risk factors for NAFLD combined with T2DM in adolescents. Controlling weight effectively is urgent to NAFLD patients with a diabetes family history in adolescents.

Association between retinal artery lesions and nonalcoholic fatty liver disease

Objective

Retinal artery lesions have been reported to be a risk marker of morbidity and mortality for cardiovascular and cerebrovascular diseases in various study populations. Nonalcoholic fatty liver disease (NAFLD) is also a risk factor for cardiovascular disease. However, the relationship between retinal artery lesions and NAFLD is less certain.

Methods

Data were obtained from 2,454 patients who attended their annual health examination (2,143 males and 311 females, aged 62.34 ± 10.03 years). NAFLD was diagnosed by hepatic ultrasonography. Retinal artery lesions were diagnosed according to the criteria. Total plasma cholesterol, plasma triglyceride and fasting glucose levels were determined by using a multichannel analyzer; the body mass index, systolic blood pressure, diastolic blood pressure, incidence of hypertension and coronary artery disease were measured or analyzed by statistical analysis.

Results

Patients with NAFLD had older age and higher values of BMI, systolic blood pressure, diastolic blood pressure, fasting glucose, total cholesterol and triglycerides and had a higher incidence of hypertension, coronary artery disease and retinal artery lesions (p < 0.01). Retinal artery lesions were taken as a dependent variable, and age, gender, BMI, systolic blood pressure, diastolic blood pressure, fasting glucose, total cholesterol and triglyceride levels, and NAFLD were taken as covariates. We found that age ≥65 years (p < 0.01, OR 1.968), being male (p < 0.01, OR 1.668), BMI ≥ 25 (p < 0.01, OR 0.743), SBP ≥ 140 mmHg (p < 0.01, OR 1.368) and NAFLD (p < 0.01, OR 2.378) were significantly associated with a risk of retinal artery lesions by binary logistic regression analysis.

Conclusions

Patients with NAFLD were older and had higher values for BMI, systolic blood pressure, diastolic blood pressure, fasting glucose, total cholesterol and triglycerides, and higher incidence of hypertension, coronary artery disease and retinal artery lesions. NAFLD is a risk factor for retinal artery lesions.

Nonalcoholic fatty liver disease and vascular disease: State-of-the-art

Nonalcoholic fatty liver disease (NAFLD), the most common of chronic liver disease in Western Country, is closely related to insulin resistance and oxidative stress and includes a wide spectrum of liver diseases ranging from steatosis alone, usually a benign and non-progressive condition, to nonalcoholic steatohepatitis (NASH), which may progress to liver fibrosis and cirrhosis. NAFLD is considered the hepatic manifestation of the metabolic syndrome with which shares several characteristics, however recent data suggest that NAFLD is linked to increased cardiovascular risk independently of the broad spectrum of risk factors of metabolic syndrome. Accumulating evidence suggests that the clinical burden of NAFLD is not restricted to liver-related morbidity and mortality, with the majority of deaths in NAFLD patients related to cardiovascular disease and cancer and not to the progression of liver disease. Retrospective and prospective studies provide evidence of a strong association between NAFLD and subclinical manifestation of atherosclerosis (increased intima-media thickness, endothelial dysfunction, arterial stiffness, impaired left ventricular function and coronary calcification). A general agreement emerging from these studies indicates that patients with NASH are at higher risk of cardiovascular diseases than those with simple steatosis, emphasizing the role of chronic inflammation in the pathogenesis of atherosclerosis of these patients. It is very likely that the different mechanisms involved in the pathogenesis of atherosclerosis in patients with NAFLD have a different relevance in the patients according to individual genetic background. In conclusion, in the presence of NAFLD patients should undergo a complete cardiovascular evaluation to prevent future atherosclerotic complications. Specific life-style modification and aggressive pharmaceutical modification will not only reduce the progression of liver disease, but also reduce morbidity for cardiovascular disease improving overall prognosis and survival.

Nonalcoholic fatty liver disease and the heart in children and adolescents

Over the last two decades, the rise in the prevalence rates of overweight and obesity explains the emergence of nonalcoholic fatty liver disease (NAFLD) as the leading cause of chronic liver disease worldwide. As described in adults, children and adolescents with fatty liver display insulin resistance, glucose intolerance, and dyslipidemia. Thus NAFLD has emerged as the hepatic component of the metabolic syndrome (MetS) and a strong cardiovascular risk factor even at a very early age. Several studies, including pediatric populations, have reported independent associations between NAFLD and markers of subclinical atherosclerosis including impaired flow-mediated vasodilation, increased carotid artery intima-media thickness, and arterial stiffness, after adjusting for cardiovascular risk factors and MetS. Also, it has been shown that NAFLD is associated with cardiac alterations, including abnormal left ventricular structure and impaired diastolic function. The duration of these subclinical abnormalities may be important, because treatment to reverse the process is most likely to be effective earlier in the disease. In the present review, we examine the current evidence on the association between NAFLD and atherosclerosis as well as between NAFLD and cardiac dysfunction in the pediatric population, and discuss briefly the possible biological mechanisms linking NAFLD and cardiovascular changes. We also address the approach to treatment for this increasingly prevalent disease, which is likely to have an important future global impact on the burden of ill health, to prevent not only end-stage liver disease but also cardiovascular disease.

Physical activity, sedentary time, and liver enzymes in adolescents: the HELENA study

BACKGROUND

To examine the association between physical activity (PA) and liver enzyme levels in adolescents from nine European countries.

METHODS

The study comprised 718 adolescents (397 girls). PA was measured by accelerometry and expressed as total PA (counts/min), and time (min/d) engaged in moderate to vigorous intensity PA (MVPA). Time spent sedentary was also objectively measured. We measured serum levels of alanine aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyltransferase (GGT), and the AST/ALT ratio was computed.

RESULTS

There was an association between MVPA and AST and AST/ALT (age, sex, and center-adjusted β = 0.096, 95% confidence interval (CI): 0.016 to 0.118; and β = 0.090, 95% CI: 0.006 to 0.112, respectively). Meeting the PA recommendations (60 min/d of MVPA) was significantly associated with higher AST and AST/ALT, which persisted after further adjusting for sedentary time and waist circumference. Sedentary time was not associated with any of the studied liver enzyme levels.

CONCLUSION

Meeting the current PA recommendations of 60 min/d of MVPA is associated with higher levels of AST and AST/ALT regardless of time spent sedentary as well as total and central body fat in European adolescents.

A review on the genetic, environmental, and lifestyle aspects of the early-life origins of cardiovascular disease

This article is a comprehensive review on developmental origins of health and disease regarding various factors related to the origins of cardiovascular diseases from early life. It presents a summary of the impacts of various factors such as epigenetics; gene-environment interaction; ethnic predisposition to cardiovascular diseases and their underlying risk factors; prenatal factors; fetal programming; maternal weight status and weight gain during pregnancy; type of feeding during infancy; growth pattern during childhood; obesity; stunting; socioeconomic status; dietary and physical activity habits; active, secondhand, and thirdhand smoking, as well as environmental factors including air pollution and global climate change on the development and progress of cardiovascular diseases and their risk factors. The importance of early identification of predisposing factors for cardiovascular diseases for primordial and primary prevention of cardiovascular diseases from early life is highlighted.

Atherosclerosis subclinical and inflammatory markers in obese and nonobese children and adolescents

We conducted a systematic review of intima-media thickness(IMT) and inflammatory markers, compared IMT and identified by meta-analysis related to EMI and inflammatory variables in obese and non-obese children and adolescents. We searched for articles in databases Pubmed, Bireme and Science Direct, during years 2000 to 2010, with the following key words in English: "obesity", "adolescents", "atherosclerosis" and "child ", They were used in two combinations: obesity + adolescents + atherosclerosis + child + obesity and atherosclerosis. We used meta-analysis to compare IMT between obese and non-obese patients. We carefully selected 16 articles for final analysis. There were differences in the thickness of IMT between obese and non-obese patients in 12 studies, confirmed by meta-analysis. Obese patients had concentrations of C-reactive protein higher in 13 articles analyzed (p < 0.05) and lower adiponectin levels in 4 (p < 0.05). In general, obese men had lower concentrations of adiponectin and higher values of IMT and C-reactive protein than non-obese men, showing the relationship between obesity and early inflammatory process. We concluded that there is a relationship of obesity with increased IMT and changes in concentrations of inflammatory markers in this phase.

Endothelial wall thickness, cardiorespiratory fitness and inflammatory markers in obese and non-obese adolescents

BACKGROUND

Increased carotid intima-media thickness (c-IMT) is considered a marker of early-onset atherosclerosis and it has been found in obese children and adolescents, but the risk factors associated with this population remain to be elucidated.

OBJECTIVE

To compare and verify the relationship between c-IMT, metabolic profile, inflammatory markers, and cardiorespiratory fitness in obese and non-obese children and adolescents.

METHOD

Thirty-five obese subjects (19 boys) and 18 non-obese subjects (9 boys), aged 10-16 years, were included. Anthropometry, body composition, blood pressure, maximal oxygen consumption (VO2max), and basal metabolic rate were evaluated. Serum glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), blood lipids, C-reactive protein (CRP), and adiponectin were assessed. c-IMT was measured by ultrasound.

RESULTS

The results showed that c-IMT, triglycerides, insulin, HOMA-IR, and CRP values were significantly higher in the obese group than in the non-obese group, and high-density lipoprotein cholesterol (HDL-c), adiponectin, and VO2max values were significantly lower in the obese group than in the non-obese group. The c-IMT was directly correlated with body weight, waist circumference, % body fat, and HOMA-IR and inversely correlated with % free fat mass, HDL-c, and VO2max.

CONCLUSIONS

Our findings show that c-IMT correlates not only with body composition, lipids, insulin resistance, and inflammation but also with low VO2max values in children and adolescents.

Glucose homeostasis and insulin resistance: prevalence, gender differences and predictors in adolescents

BACKGROUND

Adolescence, due to transient pubertal insulin resistance (IR), is associated with a higher risk for disturbances of glucose metabolism. The aim of our study was 1) to investigate the prevalence of disturbances of glucose metabolism, 2) to define gender specific homeostasis model assessment of insulin resistance (HOMA-IR) thresholds associated with increased cardiometabolic risks and 3) to provide predictors of HOMA-IR.

METHODS

The studied cohort consisted of Czech adolescents aged 13.0-17.9 years: 1,518 individuals of general population and three studied groups according weight category (615 normal weight, 230 overweight and 683 obese). The prevalence of IR, impaired fasting glucose (IFG) and type 2 diabetes was assessed. Risky HOMA-IR thresholds based on components of metabolic syndrome were investigated. HOMA-IR prediction was calculated taking into account age, blood pressure, multiple anthropometric, biochemical and hormonal parameters.

RESULTS

In general population cohort, the prevalence of IFG and type 2 diabetes was 7.0% and <0.5%, respectively. Boys regardless of weight presented significantly higher levels of blood glucose and higher prevalence of IFG than girls. Obese boys were found more insulin resistant than obese girls. HOMA-IR thresholds of 3.6 for girls and 4.4 for boys were associated with increased cardiometabolic risks. For both genders, the model of HOMA-IR prediction was composed of age, BMI, ratio of free triiodthyronine to free thyroxine, gamma-glutamyltransferase activity and levels of triglycerides and sex hormone-binding globulin.

CONCLUSIONS

The type 2 diabetes in adolescents, including those who were obese, was rarely diagnosed. Obese adolescent boys were at greater risk for IR and for IFG than obese girls. In adolescence, thresholds of HOMA-IR in contrast to predictors were found gender specific.

Cardiorespiratory fitness, waist circumference, and alanine aminotransferase in youth

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is considered the liver component of the metabolic syndrome and is strongly associated with cardiometabolic diseases. In adults, cardiorespiratory fitness (CRF) is inversely associated with alanine aminotransferase (ALT), a blood biomarker for NAFLD. However, information regarding these associations is scarce for youth. The objective of this study is to examine associations between CRF, waist circumference, and ALT in youth.

METHODS

Data were obtained from youth (n = 2844, 12-19 yr) in the National Health and Nutrition Examination Survey 2001-2004. CRF was dichotomized into youth FITNESSGRAM categories of "low" and "adequate" CRF. Logistic and quantile regression were used for a comprehensive analysis of associations, and variables with previously reported associations with ALT were a priori included in the models.

RESULTS

Results from logistic regression suggested that youth with low CRF had 1.5 times the odds of having an ALT >30 than youth with adequate CRF, although the association was not statistically significant (P = 0.09). However, quantile regression demonstrated that youth with low CRF had statistically significantly higher ALT (+1.04, +1.05, and +2.57 U·L) at the upper end of the ALT distribution (80th, 85th, and 90th percentiles, respectively) than youth with adequate CRF. For every 1-cm increase in waist circumference, the odds of having an ALT >30 increased by 1.06 (P < 0.001), and the strength of this association increased across the ALT distribution.

CONCLUSIONS

Future studies should examine whether interventions to improve CRF can decrease hepatic fat and liver enzyme concentrations in youth with ALT ≥80th percentile or in youth diagnosed with NAFLD.

Liver function test changes in centrally obese youth with metabolic syndrome in a Serbian population

OBJECTIVE

The aim of this study was to investigate the association between metabolic syndrome and liver enzymes in overweight and obese adolescents and young adults.

METHODS

A total of 126 overweight and obese adolescents and young adults (age, 15-26 years), 55 (43.6%) with metabolic syndrome and 71 (56.4%) without metabolic syndrome, were studied.

RESULTS

Patients with metabolic syndrome had significantly higher alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), and alkaline phosphatase (ALP) levels compared to patients without metabolic syndrome [36.5±22.2 vs. 29.4±17.8 IU/L (P=0.043), 33.8±17.8 vs. 26.9±18.4 IU/L (P=0.002), and 84.3±32.2 vs. 75.7±29.5 IU/L (P=0.063)]. Aspartate aminotransferase (AST) levels were similar in both groups (24.1±9.8 vs. 23.3±9.0 IU/L, P=0.674). Elevated AST, ALT, GGT, and ALP levels were observed in 6, 15, 18, and 5 patients (11%, 27%, 14%, and 9%) with metabolic syndrome compared to 6, 17, 6, and 4 (8%, 24%, 8% and 5%) patients without metabolic syndrome (P=0.872, P=0.826, P<0.001, and P=0.035). In multivariate regression models adjusted for age and gender, metabolic syndrome was not a significant predictor of ALT (P=0.967), GGT (P=0.526), and ALP levels (P=0.221), but insulin resistance was a significant predictor for ALT and GGT levels (P=0.001, P=0.028).

CONCLUSION

Changes in liver function tests were observed in obese patients with metabolic syndrome, compared to patients without metabolic syndrome, especially in ALT and GGT levels. Insulin resistance is an independent pathogenic mechanism in liver function test changes regardless of metabolic syndrome in nondiabetic centrally obese youth.

Role of physical activity in the treatment of nonalcoholic fatty liver disease in children and adolescents

Currently, nonalcoholic fatty liver disease (NAFLD) is the most frequent liver abnormality observed in obese children and adolescents. A strong body of evidence suggests that increased liver fat is significantly associated with visceral adiposity, metabolic syndrome, and insulin resistance in obese children and adolescents. Diet and exercise are generally recommended to treat obese youth with NAFLD as they do not carry side effects and confer multiple cardiometabolic benefits. Studies in adult populations report a beneficial effect of regular physical activity on reducing liver fat. In children and adolescents, available data show that weight loss induced by increasing physical activity and calorie restriction is beneficial to reduce liver fat and associated health risk factors such as insulin resistance and dyslipidemia. Currently, evidence regarding the independent effects of regular exercise alone (e.g., without calorie restriction) on NAFLD are unclear. Additionally, there is no data regarding the optimal exercise regimen (e.g., type, dose, intensity) that should be prescribed for reducing NAFLD in children and adolescents. The purpose of this review is to examine the role of physical activity on NAFLD in children and adolescents.

The association of alanine aminotransferase within the normal and mildly elevated range with lipoproteins and apolipoproteins: the Insulin Resistance Atherosclerosis Study

AIMS/HYPOTHESIS

Markers of liver injury, such as alanine aminotransferase (ALT), have been associated with atherogenic lipoprotein changes. We examined the extent to which this association was explained by insulin resistance, adiposity, glucose tolerance and chronic inflammation.

METHODS

In this analysis we included 824 non-diabetic participants (age 40-69 years) in the Insulin Resistance Atherosclerosis Study. No participants reported excessive alcohol intake or treatment with lipid-lowering medications. Lipoproteins and apolipoproteins were measured by conventional methods and lipoprotein heterogeneity by nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

ALT had a positive relationship with triacylglycerols, LDL-to-HDL-cholesterol ratio and apolipoprotein B (ApoB) after adjusting for demographic variables (p < 0.001 for all three relationships). ALT was also associated with the following NMR lipoproteins: positively with large VLDL (p < 0.001), intermediate-density lipoprotein (IDL) (p < 0.001) and small LDL subclass particles (p < 0.001), and VLDL particle size (p < 0.001); and negatively with large LDL subclass particles (p < 0.05) and LDL (p < 0.001) and HDL particle sizes (p < 0.01). ALT remained associated with IDL and small LDL subclass particles and ApoB after adjusting for glucose tolerance, adiposity, directly measured insulin sensitivity and C-reactive protein.

CONCLUSIONS/INTERPRETATION

ALT is associated with a wide range of atherogenic lipoprotein changes, which are partially explained by insulin resistance, adiposity, glucose tolerance and chronic inflammation. Because of the significant variability in the relationship between ALT and liver fat, further studies are needed to assess the extent of the lipoprotein changes using a direct measure of liver fat.

Fatty liver is a good indicator of subclinical atherosclerosis risk in obese children and adolescents regardless of liver enzyme elevation

AIM

To investigate the presence of association between nonalcoholic fatty liver disease (NAFLD) and subclinical atherosclerosis using carotid intima media thickness (c-IMT) in obese children and adolescents. Additionally, we wished to investigate the relationship between fatty liver and elevated liver enzymes.

METHODS

A total of 157 obese patients (78 boys and 79 girls, mean age: 11.3 ± 2.6 years, age range: 6-16 years) were enrolled in the study. Aminotransferase, fasting glucose and lipid levels were determined. An oral glucose tolerance test was performed. The c-IMT was measured. Infectious and metabolic causes of elevated liver enzymes were excluded. The diagnosis of NAFLD was based on ultrasound scan.

RESULTS

Obese patients with NAFLD had markedly increased carotid IMT (mean: 0.48 mm, 95% CI: 0.47-0.49) than those without NAFLD (mean: 0.45 mm 95% CI: 0.44-0.45, p < 0.001). The presence of NAFLD significantly increased c-IMT whether the patient had elevated liver enzyme or not (ANOVA, p < 0.001). In a multiple-regression model, only the presence of NAFLD was associated with increased c-IMT (β = 0.031, SE (β) = 0.008, p < 0.001).

CONCLUSION

Obese children and adolescents with NAFLD are at risk of early atherosclerotic changes. As liver function tests are not sufficient to identify patients with fatty liver, ultrasonographic evaluation of NAFLD might be considered in all obese children and adolescents.

The relationship between pediatric nonalcoholic fatty liver disease and cardiovascular risk factors and increased risk of atherosclerosis in obese children

To investigate the relationship between nonalcoholic fatty liver disease and cardiovascular risk factors and increased risk of atherosclerosis in obese children. The study included 80 consecutive obese children who were stratified into group 1 [ultrasonographically diagnosed with NAFLD (n = 50)] and group 2 [not diagnosed with NAFLD (n = 30)]. The control group included 30 healthy children. The groups were compared in terms of clinical cardiovascular risk factors and carotid intimal medial thickness (CIMT) (as a marker of atherosclerosis) measured using B-mode ultrasound. Mean body mass index (BMI) and blood pressure (BP), as well as the frequency of dyslipidemia, metabolic syndrome (MetS), and insulin resistance (IR), were similar in groups 1 and 2. Mean BMI and triglyceride (TG) levels, and the frequency of IR and MetS, increased significantly as the grade of steatosis increased. Mean CIMT in group 1 was significantly greater than that in the control group (P < 0.01). There was a positive correlation between CIMT and age, BP, and BMI in groups 1 and 2. In addition, CIMT was correlated with TG, low high-density lipoprotein (HDL) cholesterol, MetS, and IR only in group 1. Linear regression analysis between CIMT and age, BP, BMI, TG level, HDL cholesterol level, IR, MetS, and grade of steatosis yielded a significant difference only for grade of steatosis. Cardiovascular risk factors are more impressive and CIMT was significantly higher in group 1 than in group 2 and the control group, indicating that they are associated with greater risk of atherosclerosis and future adverse cardiovascular events.

BMI, apolipoprotein B/apolipoprotein A-I ratio, and insulin resistance in patients with prolactinomas: a pilot study in a Chinese cohort

Deranged metabolic profiles and insulin resistance (IR) have been documented in patients with prolactinomas. Few data are yet available on the apolipoprotein (apo) B/apoA-I ratio and its relationship with IR in patients with prolactinomas. This study was aimed to evaluate the level of apoB/apoA-I ratio and its association with IR in a Chinese subgroup with prolactinomas. Twenty-three prolactinoma patients and 20 healthy controls were enrolled in this study. The clinical anthropometric parameters and laboratory evaluation were collected. Insulin sensitivity was estimated using homeostatic model assessment [homeostasis model assessment of insulin resistance (HOMA-IR)]. Waist circumference and body weight index (BMI) were significantly higher in patients with prolactinomas than those in the controls (p < 0.05). Meanwhile, the prevalence of general and abdominal obesity seemed more pronounced in male patients compared to that in healthy subjects (57.14 vs. 0 % and 71.43 vs. 16.7 %, respectively). Furthermore, fasting glucose, insulin, HOMA-IR, triglyceride, and apoB/apoA-I ratio were also significantly higher in prolactinoma patients, but with lower level of apoA-I (p < 0.05). Univariate regression analysis revealed that prolactin, waist circumference, BMI, and presence of hypogonadism were significantly associated with IR (p < 0.05). However, only BMI [odds ratio (OR) = 1.937, 95 % confidence interval (CI) 1.112-3.375, p = 0.02] and prolactin (OR = 5.173, 95 % CI 1.073-24.94, p = 0.041) were shown to be independent predictors for the presence of IR in multivariate logistic analysis. This study confirmed the altered metabolic profile, including body weight gain, IR, disordered lipids, and apolipoproteins in prolactinoma patients. Prolactin and BMI were independently associated with IR. The effect of apoB/apoA-I ratio on IR is warranted to be determined in further studies.

Association of anthropometric measures with cardiovascular risk factors and metabolic syndrome in normal-weight children and adolescents: the CASPIAN III study

OBJECTIVE

This nationwide study was conducted to determine the association of anthropometric measures with cardiovascular risk factors and metabolic syndrome (MetS) in Iranian normal-weight children and adolescents.

METHODS

We analyzed the data of 3,565 children and adolescents (50.3% boys), aged 10-18 years, with a normal BMI (5th-84th percentile) obtained from the third survey of 'Childhood and Adolescence Surveillance and Prevention of Adult Non-communicable Disease' (CASPIAN III) study. The diagnostic criteria for MetS were defined by the International Diabetes Federation consensus.

RESULTS

The prevalence of MetS for 10- to 13.9-year-old boys, 14- to 18-year-old boys, 10- to 13.9-year-old girls, and 14- to 18-year-old girls were 1.4, 2.8, 2.3, and 3.3%, respectively. After adjustment for age and sex, each unit increase in BMI (within normal range) and waist circumference increased the odds of MetS from 6 to 72% and from 1 to 20%, respectively. The dominant pattern of dyslipidemia among the participants was high triglycerides and low high-density lipoprotein cholesterol.

CONCLUSION

This study complements recent research about the high frequency of metabolic risk factors among normal-weight individuals in the pediatric age group.

Evaluation of carotid artery stiffness in obese children using ultrasound radiofrequency data technology

OBJECTIVES

The goals of this study were to investigate the difference in carotid arterial stiffness in obese children compared to healthy children and to study the correlation between carotid arterial stiffness parameters and obesity using ultrasound (US) radiofrequency (RF) data technology.

METHODS

Carotid artery stiffness parameters, including the compliance coefficient, stiffness index, and pulse wave velocity, were evaluated in 71 obese patients and 47 healthy controls with US RF data technology. In addition, all participants were evaluated for fat thickness in the paraumbilical abdominal wall and fatty liver using abdominal US.

RESULTS

Compared to the control group, the blood pressure (BP), body mass index (BMI), fat thickness in the paraumbilical abdominal wall, presence of fatty liver, and carotid stiffness parameters (stiffness index and pulse wave velocity) were significantly higher in the obese group, whereas the compliance coefficient was significantly lower in the obese group. Furthermore, the pulse wave velocity was weakly positively correlated with the BMI, systolic BP, diastolic BP, and paraumbilical abdominal wall fat thickness, whereas the compliance coefficient was weakly negatively correlated with the systolic BP, BMI, and paraumbilical abdominal wall fat thickness. The presence of a fatty liver was moderately positively correlated with the BMI and weakly positively correlated with the pulse wave velocity.

CONCLUSIONS

Ultrasound RF data technology may be a sensitive noninvasive method that can be used to accurately and quantitatively detect the difference in carotid artery stiffness in obese children compared to healthy children. The detection of carotid functional abnormalities and nonalcoholic fatty liver disease in obese children should allow early therapeutic intervention, which may prevent or delay the development of atherosclerosis in adulthood.

Lipoprotein metabolism in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), an escalating health problem worldwide, covers a spectrum of pathologies characterized by fatty accumulation in hepatocytes in early stages, with potential progression to liver inflammation, fibrosis, and failure. A close, yet poorly understood link exists between NAFLD and dyslipidemia, a constellation of abnormalities in plasma lipoproteins including triglyceride-rich very low density lipoproteins. Apolipoproteins are a group of primarily liver-derived proteins found in serum lipoproteins; they not only play an extracellular role in lipid transport between vital organs through circulation, but also play an important intracellular role in hepatic lipoprotein assembly and secretion. The liver functions as the central hub for lipoprotein metabolism, as it dictates lipoprotein production and to a significant extent modulates lipoprotein clearance. Lipoprotein metabolism is an integral component of hepatocellular lipid homeostasis and is implicated in the pathogenesis, potential diagnosis, and treatment of NAFLD.

Association between nonalcoholic fatty liver disease and cardiovascular risk in obese children and adolescents

BACKGROUND

The recent rise in the prevalence of obesity likely explains nonalcoholic fatty liver disease (NAFLD) epidemic worldwide. We evaluated cardiac functions, cardiovascular risk, and associated parameters with grades of NAFLD in obese children.

METHODS

Four hundred obese children were enrolled in the study. Obese children with NAFLD were classified in 2 subgroups according to ultrasonographic visualizing. Ninety-three obese children with NAFLD (mean age 11.73 ± 2.72 years in group 2 and 12.69 ± 2.61 years in group 3) were compared with 307 age- and sex-matched non-NAFLD obese children and 150 control subjects. Laboratory parameters were measured during the fasting state. Pulsed and tissue Doppler echocardiography were performed. Intima-media (IMT) and epicardial adipose tissue (EAT) thicknesses were measured.

RESULTS

NAFLD groups had a significantly higher body mass index (29.15 ± 3.42 and 30.46 ± 4.60; P < 0.001), total adipose tissue mass (37.95 ± 4.46% and 46.57 ± 6.45%; P < 0.001), higher insulin, alanine aminotransferase, and aspartate aminotransferase levels. Increased end-systolic thickness of the interventricular septum (P < 0.001), larger left ventricular mass (P < 0.003) and index (P < 0.003) were found in NAFLD groups. Children with NAFLD had higher Tei index values. Also, carotid artery IMT and EAT thickness were significantly higher in obese children. Waist and hip circumference, total cholesterol level, total adipose tissue mass, and interventricular septum were statistically different in NAFLD groups.

CONCLUSIONS

Children with NAFLD had mildly altered left and right ventricular functions and all obese children had increased IMT and EAT thickness. Also, grade of liver steatosis was positively correlated with total adipose tissue mass and interventricular septum systolic thickness.

Hepatic steatosis and low cardiorespiratory fitness in youth with type 2 diabetes

The purpose of this study was to examine the association between cardiorespiratory fitness, ectopic triglyceride accumulation, and insulin sensitivity among youth with and without type 2 diabetes. Subjects included 137 youth ages 13-18 years including 27 with type 2 diabetes, 97 overweight normoglycemic controls, and 13 healthy weight normoglycemic controls. The primary outcome measure was cardiorespiratory fitness defined as peak oxygen uptake indexed to fat free mass. Secondary outcomes included liver and muscle triglyceride content determined by (1)H-magnetic resonance spectroscopy and insulin sensitivity determined by frequently sampled intravenous glucose tolerance test. Despite similar measures of adiposity, peak oxygen uptake was 11% lower (38.9 ± 7.9 vs. 43.9 ± 6.1 ml/kgFFM/min, P = 0.002) and hepatic triglyceride content was nearly threefold higher (14.4 vs. 5.7%, P = 0.001) in youth with type 2 diabetes relative to overweight controls. In all 137 youth, cardiorespiratory fitness was negatively associated with hepatic triglyceride content (r = -0.22, P = 0.02) and positively associated with insulin sensitivity (r = 0.29, P = 0.002) independent of total body and visceral fat mass. Hepatic triglyceride content was also negatively associated with insulin sensitivity (r = -0.35, P < 0.001), independent of adiposity, sex, age, and peak oxygen uptake. This study demonstrated that low cardiorespiratory fitness and elevated hepatic triglyceride content are features of type 2 diabetes in youth. Furthermore, cardiorespiratory fitness and hepatic triglyceride are associated with insulin sensitivity in youth. Taken together, these data suggest that cardiorespiratory fitness and hepatic steatosis are potential clinical biomarkers for type 2 diabetes among youth.

Non-traditional markers of metabolic risk in prepubertal children with different levels of cardiorespiratory fitness

OBJECTIVE

To assess classical and non-classical metabolic risk biomarkers in prepubertal children with different levels of cardiorespiratory fitness (CRF).

DESIGN

CRF was assessed by the 20 m shuttle run test. To estimate physical activity, participants were observed while engaged in an after-school programme. Additionally, a short test based on a validated questionnaire was used to obtain information about physical activity practice and sedentary habits. Anthropometric parameters, blood pressure, and classical and non-traditional metabolic risk biomarkers--plasma lipid profile, glucose and insulin, homeostasis model assessment-insulin resistance index (HOMA-IR), plasma uric acid, transaminases and C-reactive protein (CRP)--were measured.

SETTING

The study was conducted in local elementary schools in Córdoba, Spain.

SUBJECTS

One hundred and forty-one healthy children (eighty-eight boys, fifty-three girls) aged 7-12 years, in Tanner stage I, were recruited. They were divided into two groups after they performed the 20 m shuttle run test: equal or higher cardiovascular fitness (EHCF) group and low cardiovascular fitness (LCF) group.

RESULTS

The LCF group displayed significantly higher TAG (P = 0.004) and lower HDL cholesterol levels (P = 0.001), as well as significantly lower values for the non-traditional lipid marker apo-A1 (P = 0.001) compared with the EHCF group. The LCF children displayed higher plasma glucose (P = 0.003) and insulin levels, higher HOMA-IR scores (P < 0.001) and higher plasma uric acid and CRP levels (P < 0.05). After adjustment for BMI, age and sex, no statistically significant differences were found between groups for the biomarkers analysed.

CONCLUSIONS

The study provides new information to understand the role not only of weight status but also of the level of CRF on the metabolic health profile of prepubertal children.

Pediatric nonalcoholic fatty liver disease, metabolic syndrome and cardiovascular risk

Nonalcoholic fatty liver disease (NAFLD) encompasses a range of liver histology severity and outcomes in the absence of chronic alcohol use. The mildest form is simple steatosis in which triglycerides accumulate within hepatocytes. A more advanced form of NAFLD, non-alcoholic steatohepatitis, includes inflammation and liver cell injury, progressive to cryptogenic cirrhosis. NAFLD has become the most common cause of chronic liver disease in children and adolescents. The recent rise in the prevalence rates of overweight and obesity likely explains the NAFLD epidemic worldwide. NAFLD is strongly associated with abdominal obesity, type 2 diabetes, and dyslipidemia, and most patients have evidence of insulin resistance. Thus, NAFLD shares many features of the metabolic syndrome (MetS), a highly atherogenic condition, and this has stimulated interest in the possible role of NAFLD in the development of atherosclerosis. Accumulating evidence suggests that NAFLD is associated with a significantly greater overall mortality than in the general population, as well as with increased prevalence of cardiovascular disease (CVD), independently of classical atherosclerotic risk factors. Yet, several studies including the pediatric population have reported independent associations between NAFLD and impaired flow-mediated vasodilatation and increased carotid artery intimal medial thickness-two reliable markers of subclinical atherosclerosis-after adjusting for cardiovascular risk factors and MetS. Therefore, the rising prevalence of obesity-related MetS and NAFLD in childhood may lead to a parallel increase in adverse cardiovascular outcomes. In children, the cardiovascular system remains plastic and damage-reversible if early and appropriate interventions are established effectively. Therapeutic goals for NAFLD should address nutrition, physical activity, and avoidance of smoking to prevent not only end-stage liver disease but also CVD.

Circulating oxidized LDL and inflammation in extreme pediatric obesity

Oxidative stress and inflammation have not been well-characterized in extreme pediatric obesity. We compared levels of circulating oxidized low-density lipoprotein (oxLDL), C-reactive protein (CRP), and interleukin-6 (IL-6) in extremely obese (EO) children to normal weight (NW) and overweight/obese (OW/OB) children. OxLDL, CRP, IL-6, BMI, blood pressure, and fasting glucose, insulin, and lipids were obtained in 225 children and adolescents (age 13.5 ± 2.5 years; boys 55%). Participants were classified into three groups based on gender- and age-specific BMI percentile: NW (<85th, n = 127), OW/OB (85th- <1.2 times the 95th percentile, n = 64) and EO (≥1.2 times the 95th percentile or BMI ≥35 kg/m(2), n = 34). Measures were compared across groups using analysis of covariance, adjusted for gender, age, and race. Blood pressure, insulin, and lipids worsened across BMI groups (all P < 0.0001). OxLDL (NW: 40.8 ± 9.0 U/l, OW/OB: 45.7 ± 12.1 U/l, EO: 63.5 ± 13.8 U/l) and CRP (NW: 0.5 ± 1.0 mg/l, OW/OB: 1.4 ± 2.9 mg/l, EO: 5.6 ± 4.9 mg/l) increased significantly across BMI groups (all groups differed with P < 0.01). IL-6 was significantly higher in EO (2.0 ± 0.9 pg/ml) compared to OW/OB (1.3 ± 1.2 pg/ml, P < 0.001) and NW (1.1 ± 1.0 pg/ml, P < 0.0001) but was not different between NW and OW/OB. Extreme pediatric obesity, compared to milder forms of adiposity and NW, is associated with higher levels of oxidative stress and inflammation, suggesting that markers of early cardiovascular disease and type 2 diabetes mellitus are already present in this young population.

Atherogenic dyslipidemia and cardiovascular risk in children with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease is now regarded as the most common form of chronic liver disease in adults and children. The close association between nonalcoholic fatty liver disease (NAFLD) and the metabolic syndrome has been extensively described. Moreover, a growing body of evidence suggest that NAFLD by itself confers a substantial cardiovascular risk independent of the other components of the metabolic syndrome. Given the significant potential for morbidity and mortality in these patients, and the large proportion of both pediatric and adult population affected, it is important that we clearly define the overall risk, identify early predictors for cardiovascular disease progression, and establish management strategies. In this article, we will focus on current data linking NAFLD and the severity of liver damage present in children with cardiovascular risk.