Endocrine Abstracts

JOINT1785

Introduction: Body mass index(BMI [kg/m²]) is the most used anthropometric parameter to estimate body fat content. However, its interpretation during childhood and adolescence has limitations, as it is not constant and varies significantly with age, sex, and maturation stage, requiring reference values and a z-score format. The triceps mass index(TMI [kg/m³]) estimates body fat percentage more accurately than BMI in children and adolescents aged 8 to 18 years. DEXA(Dual-Energy X-ray Absorptiometry) is the gold standard for tricompartimental analysis of body composition and accurately estimates body fat percentage, being the best parameter to define and classify the degree of obesity.

Objective: To analyze the correlation between body fat percentage estimated by DEXA and anthropometric parameters: TMI, BMI, and BMI z-score from the 2010 Spanish Transversal Growth Study and WHO Growth Patterns 2007 in a population of obese children and adolescents.

Patients and Methods: Sixty-six obese patients (56% female), aged between 8 and 18 years, with a mean age of 14.1±2.4 years, were included. Body composition was assessed using DEXA(Lunar Prodigy Advance DXA).

Results: The mean age of obesity onset was 6.5±2.6 years (range: 1–12 years). BMI value: 35.2±6.0; BMI z-score 2007: 3.2±0.6 (range: 2–4.4); and TMI: 22.2±4.1(range: 14.8–36.9). Eight patients(17%) had moderate obesity(BMI z-score 2007 >2; <2.5SD); 37 patients (56%) had severe obesity(BMI z-score 2007 >2.5; <3.5SD); and 21 patients (31%) had morbid obesity(BMI z-score 2007 >3.5). In DEXA body composition analysis, the mean body fat percentage was 49.5±6.2%(range: 33.8–59.6). The mean body fat percentage in females was 51.6±5.4%(range: 38.4–59.6) and in males was 46.9±6.2%(range: 33.8–57.1). A positive and significant correlation was found between body fat percentage and TMI(r = 0.55, P < 0.05), BMI(r = 0.46, P < 0.05), BMI z-score 2010(r = 0.53, P < 0.05), and BMI z-score 2007(r = 0.45, P < 0.05). Regarding sex: Males (n = 29): TMI(r = 0.39, P < 0.05), BMI(r = 0.38, P < 0.05), BMI z-score 2010(r = 0.40, P < 0.05). No significant correlation with BMI z-score 2007(r = 0.3, P = 0.1). Females (n = 37): TMI(r = 0.61, P < 0.05), BMI(r = 0.56, P < 0.05), BMI z-score 2010(r = 0.63, P < 0.05), and BMI z-score 2007(r = 0.62, P < 0.05).

Conclusions: Preliminary results from this ongoing study show that the degree of concordance between the anthropometric parameters analyzed and the body fat percentage estimated by DEXA is very similar in obese patients when analyzed by sex, although this correlation is stronger in females. Since TMI values are very consistent and comparable across both sexes in the 8–18 age range, this index would be highly useful for identifying and classifying the degree of obesity.