Metabolic implications of low muscle mass in the pediatric population: a critical review

Association between BMI z-score and body composition indexes with blood pressure and grip strength in school-age children: a cross-sectional study

Childhood obesity is linked to diverse health outcomes, including elevated blood pressure (EBP). Emerging evidence showed that excess fat mass (FM) may have a deleterious impact on blood pressure even in normal-weight children. The primary objective of this study was to assess the association between body weight status by BMI z-score and body composition parameters by conventional bioelectrical impedance analysis (BIA) and bioelectrical impedance vector analysis (BIVA). Also, we aimed to explore the performance of BMI z-score, %FM, and FM index (FMI) in discriminating EBP in a sample of school-age Mexican children. Children were classified as having normal weight, overweight or obesity according to WHO criteria for BMI z-score. FMI was considered high when above 75th percentile, and fat free mass index (FFMI) was considered low when below 25th percentile of the reference population. Body composition was also classified according to the BIVA method and EBP was determined when systolic and/or diastolic blood pressure ≥ 90th percentile. BMI z-score groups were compared by Student´s t-test or the Mann-Whitney U test, or by the chi-square test or Fisher exact test. Receiving operating characteristic (ROC) analysis was performed. 61 children were included (52.5% boys, median age 9.8 (25th, 75th percentiles: 8.5, 11.0)) years. High FMI was observed in 32.3% of children with normal weight. Low FFMI was present in 93.5% of children with normal weight and 53.3% of those with overweight/obesity. According to BIVA, 58.1% and 43.3% of children with normal weight and overweight/obesity were classified as having cachexia. All the three adiposity indicators showed significant areas under the ROC curve (AURC) greater than 0.775 for EBP, with the largest one displayed for FM% (0.794). Hight FMI and low FFMI are common in children with normal weight. Identifying deficiency of FFM might be limited by using solely BMI indicators. Cachexia by BIVA was present in a high proportion of children with either normal weight or overweight/obesity. Both BMI z-score and FM (% and FMI) performed well at discriminating EBP, with a numerically greater AURC observed for FM%. Body composition in pediatric population is relevant for identifying body composition abnormalities at early age.

The metabolic load-capacity model and cardiometabolic health in children and youth with obesity

BACKGROUND

The metabolic load-capacity index (LCI), which represents the ratio of adipose to skeletal muscle tissue-containing compartments, is potentially associated with cardiometabolic diseases.

OBJECTIVES

To examine the associations between the LCI and cardiometabolic risk factors in children and youth with obesity.

METHODS

This is a cross-sectional study including 10-18 years-old participants with a BMI of ≥95th . LCI by air-displacement plethysmography (ADP) was calculated as fat mass divided by fat-free mass, and LCI by ultrasound (US) as subcutaneous adipose tissue divided by skeletal muscle thickness. Sex-specific medians stratified participants into high versus low LCI. Single (inflammation, insulin resistance, dyslipidemia and hypertension) and clustered cardiometabolic risk factors were evaluated. Linear and logistic regression models tested the associations between these variables, adjusted for sexual maturation.

RESULTS

Thirty-nine participants (43.6% males; 59% mid-late puberty) aged 12.5 (IQR: 11.1-13.5) years were included. LCI by ADP was positively associated with markers of inflammation and dyslipidemia; having a higher LCI predicted dyslipidemia in logistic regression. Similarly, LCI by US was positively associated with markers of dyslipidemia and blood pressure. In mid-late pubertal participants, LCI by US was positively associated with markers of insulin resistance and inflammation.

CONCLUSIONS

Participants with unfavourable cardiometabolic profile had higher LCI, suggesting its potential use for predicting and monitoring cardiometabolic health in clinical settings.

Sarcopenia in long-term survivors of cancer in childhood and adolescence: A cross-sectional study of calf muscle mass by peripheral quantitative computed tomography with an examination of the muscle-bone unit

BACKGROUND

Sarcopenia, a loss of systemic skeletal muscle mass (SMM), is prevalent in childhood cancer survivors and often accompanied by increased fat mass (sarcopenic obesity [SO]). We examined whether calf muscle cross-sectional area (CSA), measured by peripheral quantitative computed tomography (pQCT), can identify sarcopenia and SO in long-term survivors of pediatric acute lymphoblastic leukemia (ALL), and explored its relationship with adjacent bone geometry.

PROCEDURES

Calf muscle CSA and CSA Z scores at the 38% tibia in 70 subjects (median survival 15 years) were compared between sexes and ALL risk group, and their association with sarcopenia and SO evaluated. Relationships between bone strength and muscle mass were assessed further using linear regression and methods described by Schoenau et al. for evaluation of a functional muscle-bone unit.

RESULTS

A calf muscle CSA Z score of less than or equal to zero is 73.81% sensitive and 84.62% specific for detecting sarcopenia defined by height-adjusted appendicular lean mass measured by dual-energy x-ray absorptiometry. No significant difference in CSA Z scores was noted between sexes or ALL risk groups; however, Z scores were markedly higher in those without SO (adjusted odds ratio 0.529, 95% confidence interval [CI]: 0.340-0.824). Ratios of calf muscle mass to height and total bone mineral content at the 38% tibia are "sufficient" and consistent with estimated reference ranges for a healthy population.

CONCLUSIONS

CSA Z scores may represent a useful clinical measure of SMM and are predictive of SO in this population. Our results are supportive of a functional muscle-bone unit in long-term survivors of pediatric ALL.

Low skeletal muscle mass and liver fibrosis in children with cerebral palsy

The purpose of the study was to conduct a nutritional and metabolic assessment of children with cerebral palsy, including an investigation of liver status, body composition, and bone mineral density. In this cross-sectional study we included 22 children with cerebral palsy. By using ultrasound, transient elastography, dual x-ray absorptiometry (DXA) scan, blood samples, anthropometric measurements, and a three-day diet registration, the nutritional and metabolic status was evaluated. Liver fibrosis and steatosis were found in four patients (18.2%), all with severe motor impairments, low skeletal muscle mass, and epilepsy. All patients with liver involvement had normal liver-related blood samples. Decreased bone mineral density was found in 26.3%, and 91.0% had low skeletal muscle mass. Fat mass and muscle mass were significantly lower in the patients with severe motor impairments compared to the patients with less severe motor impairments. Within the children classified as 'underweight' or 'normal' according to body mass index, body fat determined by DXA scan was normal or high in 50% of these patients.

CONCLUSIONS

This study is the first to report liver fibrosis and steatosis in children with cerebral palsy. Possible causes of liver fibrosis and/or steatosis are altered body composition with low skeletal muscle mass, decreased mobility and medical drug intake. Further investigations of liver involvement and risk factors are needed.

WHAT IS KNOWN

• Children and adolescents with cerebral palsy are at risk of malnutrition and altered body composition, both of which can lead to fatty liver disease. • It is unknown whether children with cerebral palsy are at increased risk of metabolic disturbances such as fatty liver disease.

WHAT IS NEW

• Altered body composition and low skeletal muscle mass, regardless of ambulation is present in 91% of the children with cerebral palsy. • Liver fibrosis and/or steatosis were found in 18.2% of the patients. Possible causes are altered body composition, decreased mobility and medical drug intake.

Estimation of skeletal muscle mass in 4-year-old children using the D3-creatine dilution method

BACKGROUND

Given limited experience in applying the creatine-(methyl-D3) (D3Cr) dilution method to measure skeletal muscle mass (SMM) in young children, the feasibility of deployment in a fielding setting and performance of the method was assessed in a cohort of 4-year-old children in Dhaka, Bangladesh.

METHODS

Following D3Cr oral dose (10 mg) administration, single fasting urine samples were collected at 2-4 days (n = 100). Twenty-four-hour post-dose collections and serial spot urine samples on days 2, 3 and 4 were obtained in a subset of participants (n = 10). Urinary creatine, creatinine, D3Cr and D3-creatinine enrichment were analyzed by liquid chromatography-tandem mass spectrometry. Appendicular lean mass (ALM) was measured by dual-energy x-ray absorptiometry and grip strength was measured by a hand-held dynamometer.

RESULTS

SMM was measured successfully in 91% of participants, and there were no adverse events. Mean ± SD SMM was greater than ALM (4.5 ± 0.4 and 3.2 ± 0.6 kg, respectively). Precision of SMM was low (intraclass correlation = 0.20; 95% CI: 0.02, 0.75; n = 10). Grip strength was not associated with SMM in multivariable analysis (0.004 kg per 100 g of SMM; 95% CI: -0.031, 0.038; n = 91).

CONCLUSIONS

The D3Cr dilution method was feasible in a community setting. However, high within-child variability in SMM estimates suggests the need for further optimization of this approach.

IMPACT

The D3-creatine (D3Cr) stable isotope dilution method was considered a feasible method for the estimation of skeletal muscle mass (SMM) in young children in a community setting and was well accepted among participants. SMM was weakly associated with both dual-energy x-ray absorptiometry-derived values of appendicular lean mass and grip strength. High within-child variability in estimated values of SMM suggests that further optimization of the D3Cr stable isotope dilution method is required prior to implementation in community research settings.

Metabolic assessment in children with neuromuscular disorders shows risk of liver enlargement, steatosis and fibrosis

AIM

The aim of this study was to conduct a metabolic and nutritional assessment of children with neuromuscular disorders, including the investigation of the liver and bone mineral density.

METHODS

In this observational study, we included 44 children with neuromuscular disorders. The nutritional status, bone health and liver were assessed by ultrasound, transient elastography, dual X-ray absorptiometry scan, blood samples, anthropometric measurements and 3-day diet registration.

RESULTS

Liver involvement was found in 31.0%: liver enlargement in 7.1%, steatosis in 4.8%, fibrosis in 14.3% and liver enlargement together with steatosis or fibrosis was found in 4.8%. These changes were found in 9/23 patients with Duchenne muscular dystrophy, 4/9 patients with spinal muscular atrophy type II and 0/12 patients with other neuromuscular diagnoses. Low bone mineral density was found in 44.0% of the patients, though the majority used daily vitamin D and calcium supplements. Vitamin D insufficiency or deficiency was found in 22.6%.

CONCLUSION

The metabolic assessment in children with neuromuscular disorders shows an increased risk of liver enlargement, steatosis and fibrosis. Possible causes are obesity, decreased mobility, low skeletal muscle mass and for a subgroup the use of glucocorticoids. The findings suggest that monitoring liver function should be part of the nutritional assessment in patients with neuromuscular disorders.

Impact of Allogeneic Hematopoietic Stem Cell Transplantation on Nutritional Status and Intake in Children

OBJECTIVES

This study aimed to describe the impact of allogeneic/haploidentical hematopoietic stem cell transplantation on nutritional status and intake in a group of children aged 2 to 18 years.

METHODS

In an observational study, data were collected prospectively. Patients were prescribed individual nutritional support by hospital routines. Anthropometrics were measured pre-transplant at hospital admission and weekly from the day of transplant (day 0) until day +28. z scores for weight, height, and BMI were calculated using Norwegian growth references to assess nutritional status. Pre-transplant diet was assessed on the day of hospitalization. Nutrient provision from enteral nutrition (EN = oral and tube) and parenteral nutrition (PN) was assessed by daily records from day +1 until day +28, or previous discharge, and compared with recommendations (RI) from the Nordic Nutrition Recommendations and ESPGHAN guidelines. Total energy intake was presented as the percentage (%) of basal metabolic rate (BMR) calculated by the Schofield equation. Macro- and micronutrient provisions were presented as medians (interquartile range) and the % of RI.

RESULTS

Twenty-eight patients, mean age 10.3 years (range 3.5-16.6), were included. Two-thirds (n = 18) had malignant diseases. At admission, mean weight Z-score was -0.3, height z scores -0.7, and BMI Z-score 0.1. Eighteen percent (n = 5) were stunted and 25% (n = 7) had overweight. At admission, 25% (n = 7) had established tube feeding, and 7% (n = 2) also had PN. No significant changes in weight z scores were detected during the studied weeks ( P = 0.454). The median daily energy provision was 115% (110-123) of BMR and proteins 1.5 (1.3-1.8) g/kg. EN was provided during a median of 93% of the studied days and provided 21% of the energy. PN was given on a median of 96% of the studied days and provided 79% of energy. RI for vitamins, magnesium, and zinc was met. Provision of copper, iodine, selenium, calcium, and phosphate was below RI.

CONCLUSIONS

Combined EN and PN providing 115% of BMR and 1.5 g/kg protein ensured stable weight by day +28 and covered RI, except for trace elements and minerals.

Muscular Fitness and Cardiometabolic Variables in Children and Adolescents: A Systematic Review

BACKGROUND

The importance of muscular fitness (MF) in the performance of activities of daily living is unequivocal. Additionally, emerging evidence has shown MF can reduce cardiometabolic risk in children and adolescents.

OBJECTIVES

The purpose of this study was to examine and summarize the evidence regarding the relationship between MF phenotypes (i.e., maximum muscular strength/power, muscular endurance, and maximum muscular strength/power/endurance) and cardiometabolic variables (obesity, blood pressure, lipids, glucose homeostasis, inflammatory markers, and clustered cardiometabolic variables) in children and adolescents.

DESIGN

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number CRD42020179273.

DATA SOURCES

A systematic review was performed on five databases (PubMed, EMBASE, SciELO, Scopus, and Web of Knowledge) from database inception to May 2020, with complementary searches in reference lists.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) a study sample of youth aged ≤ 19 years, (2) an assessment of MF with individual or clustered cardiometabolic variables derived from adjusted models (regardless of test/measurement adopted or direction of reported association), and (3) a report of the association between both, using observational studies. Only original articles published in peer-reviewed journals in English, Portuguese, and Spanish languages were considered. The quality of the included studies was assessed by using the National Heart, Lung, and Blood Institute checklist. The percentage of results reporting a statistically significant inverse association between each MF phenotype and cardiometabolic variables was calculated.

RESULTS

Of the 23,686 articles initially identified, 96 were included (77 cross-sectional and 19 longitudinal), with data from children and adolescents from 35 countries. The score for the quality of evidence ranged from 0.33 to 0.92 (1.00 maximum). MF assessed by maximum muscular strength/power was inversely associated with lower obesity (64/113 total results (56.6%)) and reduction in clustered cardiometabolic risk (28/48 total results (58.3%)). When assessed by muscular endurance, an inverse association with obesity (30/44 total results (68.1%)) and cardiometabolic risk (5/8 total results (62.5%)) was identified. Most of the results for the relationship between MF phenotypes with blood pressure, lipids, glucose homeostasis, and inflammatory markers indicated a paucity of evidence for these interrelationships (percentage of results below 50.0%).

CONCLUSION

MF assessed by maximum muscular strength/power or muscular endurance is potentially associated with lower obesity and lower risk related to clustered cardiometabolic variables in children and adolescents. There is limited support for an inverse association between MF with blood pressure, lipids, glucose homeostasis biomarkers, and inflammatory markers in children and adolescents.

The associations of muscle mass with glucose and lipid metabolism are influenced by body fat accumulation in children and adolescents

OBJECTIVE

To evaluate the prevalence of hyperglycemia and dyslipidemia among different body composition and investigate the associations of body composition indicators, especially the muscle mass, with glucose and lipids metabolism in children and adolescents.

METHODS

This nationwide cross-sectional study included 8,905 children and adolescents aged 6 to 18 years. All participants underwent dual-energy x-ray absorptiometry and their blood-concentrated glucose and lipids (including TC, TG, LDL-C and HDL-c) were measured. Mixed model, hierarchical analysis, and piecewise regression were used to study the effect of body composition indicators, especially the muscle mass, on glucose and lipids metabolism.

RESULTS

The greatest prevalence of high total cholesterol (TC, 6.9% and 6.9%) and high triglyceride (22.3% and 6.6%) was found in both boys and girls with high muscle mass and high fat mass, and girls with high muscle mass and high fat mass also had the highest prevalence of hyperglycemia (7.1%). After fat stratification, higher muscle mass was associated with lower odds of hyperglycemia (OR = 0.62; 95%CI: 0.46,0.84; P = 0.002) and muscle mass was inversely associated with TC (β = -0.07; 95%CI: -0.12,-0.03; P < 0.001) in boys with normal fat mass, but high muscle mass was not significantly associated with hyperglycemia and TC in high-fat-mass group (P = 0.368 and 0.372).

CONCLUSIONS

The body composition phenotype of high muscle and high fat mass have the highest prevalence of dysglycemia and dyslipidemia. Higher muscle mass was associated with a lower risk of hyperglycemia and TC levels in individuals only with normal fat mass.

Using Body Composition Groups to Identify Children and Adolescents at Risk of Dyslipidemia

The impact of body composition on the early origin of chronic diseases is an increasingly appreciated phenomenon. Little is known about the characteristics of children with varying body composition. The aim of this study was to investigate serum lipid profiles and other characteristics in relation to body composition. The data of 1394 participants (aged 6 to <18 years) of the observational general population-based Austrian LEAD Study have been analyzed. Body composition groups were defined by appendicular lean mass (ALMI) and fat mass (FMI) indices assessed by DXA. Serum lipid profiles (triglycerides, LDL-c, HDL-c) and other characteristics (e.g., prematurity, smoke exposure, physical activity, nutrition) were investigated in these body composition groups. Different body composition groups, which are not distinguishable by BMI, exist. Children with high ALMI and high FMI showed higher triglycerides and LDL-c, but lower HDL-c levels. In contrast, levels did not differ between those with high FMI but low (or normal) ALMI, and other body composition groups. BMI should be interpreted cautiously, and body composition should be measured by more precise techniques. In particular, children and adolescents with high FMI who have concomitantly high ALMI should be followed closely in future studies to investigate whether they are at increased risk of cardiovascular problems.

Association of muscle mass and fat mass on low-density-lipoprotein cholesterol and triglyceride plasma concentration in children and adolescents

OBJECTIVES

Obesity has often been associated with high low-density-lipoprotein cholesterol (LDL-C) and triglyceride plasma concentrations, known risk factors for diabetes mellitus and cardiovascular disease. Study objective was to evaluate the association of LDL-C and triglyceride plasma concentration with muscle and fat mass in children and adolescents.

METHODS

We analyzed data of the National Health and Nutrition Examination Survey (1999-2004) to estimate lean muscle and fat mass assessed by dual-energy X-ray absorptiometry (DXA) of participants whose lipid profiles had been examined. Fat mass was operationalized by DXA-determined fat mass index (FMI). Muscle mass was assessed by appendicular lean mass index (aLMI). High LDL-C and triglyceride concentration was defined as above 130 mg/dL.

RESULTS

For the evaluation of the association of LDL-C and triglyceride plasma concentration with LMI and FMI Z-scores, the data of 2,487 children and adolescents (age 8-19 years) (984 females) were eligible. High aLMI showed no association with LDL-C or triglyceride concentration, but high FMI showed significant association with LDL-C and triglyceride plasma concentration in the bivariate regression analysis.

CONCLUSIONS

Isolated muscle mass increase may not be protective against high LDL-C and triglycerides plasma levels in children and adolescents. Thus, exercise may lead to risk factor reduction mainly through fat mass reduction.

Normalization of Muscle Strength Measurements in the Assessment of Cardiometabolic Risk Factors in Adolescents

Muscle strength (MS) has been associated with cardiometabolic risk factors (CMR) in adolescents, however, the impact attributed to body size in determining muscle strength or whether body size acts as a confounder in this relationship remains controversial. We investigated the association between absolute MS and MS normalized for body size with CMR in adolescents. This was a cross-sectional study comprising 351 adolescents (44.4% male; 16.6 ± 1.0 years) from Brazil. MS was assessed by handgrip and normalized for body weight, body mass index (BMI), height, and fat mass. CMR included obesity, high blood pressure, dyslipidemia, glucose imbalance, and high inflammation marker. When normalized for body weight, BMI, and fat mass, MS was inversely associated with the presence of two or more CMR among females. Absolute MS and MS normalized for height was directly associated with the presence of two or more CMR among males. This study suggests that MS normalized for body weight, BMI, and fat mass can be superior to absolute MS and MS normalized for height in representing lower CMR among females. Absolute MS and MS normalized for height were related to higher CMR among males.

Adiposity in Survivors of Cancer in Childhood: How is it Measured and Why Does it Matter?

Survival of cancer in childhood is increasingly common with modern therapeutic protocols but leads frequently to adverse long-term impacts on health, including metabolic and cardiovascular disease. Changes in body composition, especially an increase in fat mass and a decrease in muscle mass, are found early in patients with pediatric cancer, persist long after treatment has been completed and seem to contribute to the development of chronic disease. This review details the effects of such changes in body composition and reviews the underlying pathophysiology of the development of sarcopenic obesity and its adverse metabolic impact. The authors discuss the particular challenges in identifying obesity accurately in survivors of pediatric cancer using available measurement techniques, given that common measures, such as body mass index, do not distinguish between muscle and adipose tissue or assess their distribution. The authors highlight the importance of a harmonized approach to the assessment of body composition in pediatric cancer survivors and early identification of risk using "gold-standard" measurements. This will improve our understanding of the significance of adiposity and sarcopenia in this population, help identify thresholds predictive of metabolic risk, and ultimately prevent or ameliorate the long-term metabolic and cardiovascular impacts on health experienced by survivors of cancer in childhood.

Reference charts for body composition parameters by dual-energy X-ray absorptiometry in European children and adolescents aged 6 to 18 years-Results from the Austrian LEAD (Lung, hEart, sociAl, boDy) cohort

BACKGROUND

DXA is a widely used technique to assess body composition. Reference values based on a large general population cohort of European children and adolescents were missing. The aim of this study was to provide age- and sex-specific reference percentiles of body composition parameters for European children and adolescents and to compare them to the American NHANES cohort. Additionally, exponents accounting best for height biases were analysed.

METHODS

DXA scans of 1573 participants, aged 6 to 18 years, recruited from 2011 to 2019 by the Austrian LEAD study, a representative population-based cohort, have been used to create reference charts using the LMS model.

RESULTS

Reference charts displaying percentile curves and the corresponding reference values are provided. Fat mass parameters were higher in females, while lean mass parameters were higher in males. Compared to the NHANES cohort medians of FMI and LMI were always lower. For FMI, BMI, LMI and ALMI the best fitting exponent were 2.5, 3, 3 and 3.5 respectively CONCLUSIONS: The present study provides reference charts for children and adolescents aged 6 to 18 years, for body composition parameters assessed by DXA. The charts enable comparison to a European general-population cohort and indicate that reference populations should be chosen with caution.