Factors beyond Body Mass Index Associated with Cardiometabolic Risk among Children with Severe Obesity.

: The increasing prevalence of severe obesity among children and adolescents poses a significant challenge for pediatricians and general practitioners. This study aimed to investigate the relationships between biochemical results, anthropometry, blood pressure measurements, and bioimpedance analysis (BIA)-derived parameters to identify potential cardiometabolic complications associated with severe obesity. : This study included 347 children (162 boys, 185 girls) aged 0-19 years, meeting the criteria for severe obesity based on BMI thresholds for different age groups. The patients were recruited in four pediatric endocrinology centers in Poland (Zabrze, Cracow, Rzeszow, Szczecin). Each participant underwent anthropometric measurements, pubertal stage assessment, blood pressure measurement, biochemical and hormonal tests, and BIA. : BMI showed significant associations with fat mass percentage (FM%) and waist-to-height ratio (WHtR) but not waist-to-hip ratio (WHR). The relationship between BMI and FM% was stronger in girls and prepubertal children. The metabolic syndrome (MetS) Z-score showed a strong positive correlation with BMI in the pubertal children. A negative correlation between HDL and triglycerides was observed only in the boys. The prepubertal children exhibited more significant correlations, despite a smaller sample size and shorter duration of obesity. : Considering multiple parameters beyond BMI alone provides a better understanding of cardiometabolic risks associated with severe obesity in children. MetS Z-score was not a reliable indicator of increased cardiometabolic risk in younger children. Early-onset severe obesity was associated with a higher risk of metabolic complications. Early intervention is crucial to mitigate metabolic complications in this population.