Ultrasound measurements of subcutaneous adipose tissue thickness show sexual dimorphism in children of three to five years of age.

Aim: A standard approach to measure subcutaneous adipose tissue (SAT) using ultrasound has proved successful in adults, but has not been studied in children. This study addressed that gap in children aged three to five years.

Methods: In autumn 2016, 24 preschools in Southwest Germany, recruited via mail, agreed to take part in this study and 274 children (51.4% boys) with a mean age of 4.6 ± 0.7 years participated in measurements of SAT and anthropometry. Differences in measurements were explored between the sexes and anthropometric predictors of mean SAT thickness were identified. Intra-observer reliability for ultrasound measurements of SAT was also assessed.

Results: The mean SAT thickness showed significant differences between the boys and girls (5.3 ± 2.0 and 6.3 ± 2.0 mm, respectively, p < 0.01). The children's body mass, height and sex explained 66% of the variance in the mean SAT thickness, as SAT was larger with a higher body mass, a smaller stature and in girls. Intra-observer reliability resulted in an intra-class correlation coefficient of 0.994 (p < 0.01) with a 95% confidence interval of 0.983-0.998.

Conclusion: Subcutaneous adipose tissue thickness differed between boys and girls with a mean age of 4.6 years. Intra-observer reliability was excellent. This standardised approach enabled high-precision measurements of SAT in a paediatric population.