Subcutaneous Adipose Tissue Measured by B-Mode Ultrasound to Assess and Monitor Obesity and Cardio-Metabolic Risk in Children and Adolescents

Abstract

Monitoring of children at heightened risk of cardio-metabolic diseases raises the need for accurate assessment of obesity. A standardized approach for measuring subcutaneous adipose tissue (SAT) by bright-mode ultrasound was evaluated in relation to body indices and anthropometry in a cross-sectional sample of 76 South African children (7-10 years) and 86 adolescents (13-17 years) to assess cardio-metabolic risk. SAT was higher in girls as compared to boys (children: 50.0 ± 21.7 mm > 34.42 ± 15.8 mm, adolescents: 140.9 ± 59.4 mm > 79.5 ± 75.6 mm, p < 0.001) and up to four times higher in adolescents than in children. In children, measures of relative body weight showed only a poor correlation to SAT (BMI: r = 0.607, p < 0.001), while in adolescents, BMI correlated high with SAT (r = 0.906, p < 0.001) based on high rates of overweight and obesity (41.8%). Children with identical BMIs may have large differences (>2-3-fold) in their amount of SAT. The moderate association to systolic (r = 0.534, r = 0.550, p < 0.001) and diastolic blood pressure (r = 0.402, r = 0.262, p < 0.001) further substantiates that SAT measured by ultrasound provides an accurate, safe and easy applicable approach for monitoring in children and adolescents at cardio-metabolic risk.

Keywords: BMI; adolescent overweight/obesity; body fat assessment; cardio–metabolic risk; childhood overweight/obesity; subcutaneous adipose tissue; ultrasound.

Figure 1

Correlation between subcutaneous adipose tissue (SAT) and BMI in children (A) and adolescents (B). Note that the correlation in children is biased when including extreme cases and drops almost to zero (r = 0.030) when including only the mean 50% of the child sample. As indicated by two cases in the plot, two children or adolescents with almost identical BMIs may differ largely in their amount of SAT (>200%). Despite the high correlation in adolescents, this holds true for many cases.

Figure 2

Subcutaneous adipose tissue measured at lower abdomen in two 16-year-old girls with similar BMIs. Note that, although the two girls have almost identical BMIs, the amount of SAT is more than the two-fold in the girl at the right side. Mind that the reference lengths were 6 cm in case 36 (left) and 8 cm in case 27 (right).