Assessment of blood biomarkers in adolescents classified by body mass index and body fat percentage

Exploring the complex dynamics of BMI, age, and physiological indicators in early adolescents

BACKGROUND AND OBJECTIVES

To investigate the relationship between body mass index (BMI) and blood biochemical indicators in early adolescence, and to provide ideas for early prevention of diseases and explore possible disease-related predictors.

METHODS

3125 participants aged 10 ∼ 14 years were selected from China from the survey of "China Nutrition and Health Surveillance ( 2016 ∼ 2017 ) ". Employing advanced statistical methods, including generalized linear models, heatmaps, hierarchical clustering, and generalized additive models, the study delved into the associations between BMI and various biochemical indicators.

RESULTS

In early adolescence, indicators including systolic pressure, diastolic pressure, weight, height, BMI, hemoglobin, blood uric acid, serum creatinine, albumin, vitamin A presented increasing trends with the increase of age ( P < 0.05 ), whereas LDL-C, vitamin D, and ferritin showed decreasing trends with the increase of age ( P < 0.05 ). The increase in hemoglobin and blood uric acid levels with age was more pronounced in males compared to females ( P < 0.05 ). BMI was positively correlated with blood glucose, hemoglobin, triglyceride, LDL-C, blood uric acid, serum creatinine, ferritin, transferrin receptor, hs-CRP, total protein, vitamin A ( P < 0.05 ). There was a significant BMI × age interaction in the correlation analysis with LDL-C, transferrin receptor, serum creatinine, and hs-CRP ( P < 0.05 ). BMI was a risk factor for hypertension, hypertriglyceridemia, low high density lipoprotein cholesterolemia, and metabolic syndrome in all age groups ( OR > 1, P < 0.05 ).

CONCLUSIONS

High BMI was a risk factor for hypertension, hypertriglyceridemia, low high density lipoprotein cholesterolemia, and MetS in early adolescents. With the focus on energy intake beginning in early adolescence, the maintenance of a healthy weight warrants greater attention.

Appropriate neck circumference and waist-to-height ratio cut-off points as predictors of obesity and cardiovascular risk in adolescents

OBJECTIVE

To determine neck circumference (NC) and waist-to-height ratio (WHtR) cut-off points as predictors of obesity and cardiovascular risk in adolescents.

METHODS

Cross-sectional study developed with a subsample of 634 adolescents aged 18 and 19 years belonging to the third phase of the "RPS" cohort (Ribeirão Preto, Pelotas and São Luís) carried out in 2016. The area under the ROC curve (AUC) was identified to assess the predictive capacity of NC and WHtR in relation to the percentage of body fat (%BF), obtained by air displacement plethysmography (ADP), and the cardiovascular risk estimated by the Pathobiological Determinants of Atherosclerosis in Youth (PDAY).

RESULTS

The prevalence of obesity by %BF was 7.6% in males and 39.4% in females (p-value <0.001), and the high PDAY risk was 13.8% and 10.9%, respectively. For males, NC cut-off point was 44.0 cm and the AUCs were 0.70 (95%CI 0.58-0.83) to predict obesity and 0.71 (95%CI 0.62-0.80) to predict high cardiovascular risk; for females, NC cut-off point was 40 cm and the AUCs were 0.75 (95%CI 0.69-0.80) and 0.63 (95%CI 0.53-0.73), respectively. WHtR cut-off point was 0.50 for both sexes; for males, the AUCs to predict obesity and high risk according to PDAY were 0.90 (95%CI 0.80-0.99) and 0.73 (95%CI 0.63-0.82), respectively; for females, they were 0.87 (95%CI 0.83-0.90) and 0.55 (95%CI 0.45-0.65), respectively.

CONCLUSION

WHtR and NC are good discriminators to assess obesity and cardiovascular risk in adolescents, especially in males.

Waist-to-height ratio cut-off points to predict obesity in adolescents and associa-tion with inflammatory markers

Introduction

Introduction: obesity increases inflammatory molecules and cardiovascular risk even in young populations. New indicators are being investigated, including the waist-to-height ratio (WHtR) to predict obesity and the relationship with inflammatory markers in childhood and adolescence. Objective: to identify the cut-off points of the WHtR to determine obesity and its association with inflammatory markers in adolescents in São Luís, state of Maranhão, Brazil. Methods: this is a cross-sectional study, with 2,209 adolescents aged 18 and 19, belonging to the third phase of the birth cohort entitled "RPS", carried out in 2016. The total area under the ROC curve (AUC) was identified to assess the predictive capacity of WHtR in relation to body fat percentage (%BF), obtained by air displacement plethysmography (ADP). The association of WHtR with inflammatory markers interleukin-6 (IL-6), tumor necrosis factor (TNF-α) and c-reactive protein (CRP) was evaluated. Results: prevalence of obesity by the %BF was 10.3 % in males and 40.4 % in females. The cut-off points for the WHtR were 0.50 for females and 0.51 for males, with an AUC of 0.90 (95 % CI: 0.88-0.92) and 0.93 (95 % CI: 0.90-0.97). There was an association of elevated WHtR with higher levels of IL-6 and CRP (p < 0.05). Conclusion: the predictive capacity of WHtR for obesity was excellent. Elevated values of the WHtR were associated with early inflammatory markers. This study contributed to the identification of cut-off points for simple and low-cost anthropometric indicators.

Body phenotypes and sexual maturation in Brazilian and US adolescents: evidence for a change in BMI category

OBJECTIVE

Our study aimed to describe body phenotypes (BP) estimated by multivariate analysis and their association with body mass.

DESIGN

BP were defined based on demographic variables, anthropometric data (body mass, height, skinfolds and circumferences), body composition (phase angle measured by bioelectrical impedance analysis), biochemical parameters (TAG, glucose, total cholesterol ratio/LDL, Hb and sexual maturation (pubic hair and breasts or gonads). ANOVA was performed to verify the differences between skin colour and the stages of pubertal development, BP, body composition, anthropometric and biochemical variables.

SETTING

Cities of São Paulo-SP, Piracicaba-SP and Florianópolis-SC from Brazil and the United States.

PARTICIPANTS

9269 adolescents aged between 10 and 15 years old.

RESULTS

The composition of BP was similar in all surveys, which are: BP1 was composed by skinfolds, body mass and circumferences variables; BP2 by pubic hair, breast in girls or gonad in boys, height and age; BP3 by cholesterol, TAG and glucose; and BP4 by phase angle, Hb and glucose (negative loading). There was a strong correlation (r = 0·9, P < 0·001) between BP1 and BMI.

CONCLUSION

We highlighted independence observed between biochemical parameters, anthropometry, body composition and sexual maturation. BP may support the calculation of scores for diagnosis of obesity based on anthropometric variables and overcome ambiguity in the isolated use of BMI.

Cardiometabolic risk in adolescents with normal weight obesity

BACKGROUND

Normal weight obesity (NWO), which is defined by the excess of body fat in normal weight individuals, has been neglected among adolescents, due to their normal weight and young age. Few studies were carried out on the topic with adolescents.

OBJECTIVE

To analyze whether the NWO is associated with cardiometabolic risk factors in adolescents.

SUBJECTS/METHODS

Cross-sectional study, with 506 normal weight adolescents aged 10-19 years, selected in schools in Brazil. Weight, height, waist circumference (WC) and neck circumference were obtained and the body mass index (BMI) and waist/height ratio (WHR) were calculated. Body composition analysis was performed using dual-energy X-ray absorptiometry. The clinical evaluation included lipid and glycid profile, platelets, leukocytes, lymphocytes, monocytes, uric acid and blood pressure, as well as the presence of metabolic syndrome (MS) and its components. NWO was defined by the presence of normal weight, according to BMI for age, and excess body fat (≥25% and ≥30% in males and females, respectively). Logistic regression models were used to analyze associations between normal weight adolescents with and without the NWO phenotype.

RESULTS

NWO associated positively with abdominal obesity, analyzed through WC (OR = 1.36;95%CI = 1.27-1.47), WHR (OR = 25.89;95%CI = 10.43-64.26) and android fat (OR = 1.49;95%CI = 1.36-1.63); insulin resistance (OR = 4.09;95%CI = 1.72-9.70), hyperinsulinemia (OR = 3.83;95%CI = 1.50-9.76) and the highest values of the triglycerides-glycemia index (OR = 4.28;95%CI = 1.21-15.08); uric acid (OR = 1.81;95%CI = 1.29-2.55), as well as the changes in LDL (OR = 3.39;95%CI = 1.47-7.81), total cholesterol (OR = 2.77;95%CI = 1.22-6.29), and in at least one (OR = 1.87;95%CI = 1.04-3.37) or two (OR = 6.61;95%CI = 1.45-30.19) components of MS.

CONCLUSION

NWO is associated with the presence of cardiometabolic risk factors in adolescents.