Introduction: The harmfull or benefical effect of obesity on bone mineral density (BMD) is remain controversial in children and adolescence. Either increase or decrease of BMD have been reported. Several factors such as insülin resistance, prediabetes, high proportion of fat mass, sedentary lifestyle were suggested to cause the differences of BMD in obesity. FGF-21 is a metabolic factor that plays a specific role in the regulation of carbohydrate and lipid metabolism. However, the role of FGF-21 in bone metabolism seems somewhat paradoxical and complex. While improving of metabolic health, risk of reducing the bone health is supected in experimental studies.
Objective: This study aims to find the differences of BMD from obese children and adolescent with metabolically healthy (MHO) and unhealthy obeses (MUO) compared to the healthy controls; and its relationship between metabolic parameters including serum FGF21 levels.
Methods: There were 92 participants for the obesity group and 44 for the control group; a total of 142 patients, aged 8 to 18 years. BMD, in addition to the routine obesity workup, which includes fasting blood glucose, fasting insulin levels, lipid profile and liver enzymes; serum FGF21 levels have been analysed. Being metabolically healthy was investigated either based on without "metabolic syndrome (MS)" and "Cardiometabolic risk factor clustering (CMRFC)", and the correlation between BMD have been studied.
Results: Compared to the control group BMD z-score is significantly elevated in the obese group (1.19±1.4 g/cm2 vs 0.48±1.7g/cm2, P:0.013). MHO had higher BMD z-score (obese without MS 1.22±1.54 g/cm2, obese without CMRFC 1.45±1.7 g/cm2) than either MUO (obese with MS 1.09±1.2 g/cm2, obese with CMRFC 1.01±1.2 g/cm2) and healthy controls (P:0.044, and 0.016). The FGF-21 were not significantly different among the participants who are MHO, MUO, and the control group (P>0,05). There are no significant difference between the FGF21 levels and bone density z-score levels among the male and female participants of obese and the control groups (P>0,05). The serum levels of fasting blood glucose, fasting insülin level, and lipids were not correlated to BMD z score.
Conclusion: Although we could not find any correlation among BMD-z score and metabolic parameters including insülin and FGF21 levels; being metabolically heatlhy was lead to have highest BMD. Even though the bone density levels are significantly elevated among the obese group compared to the control group, it is found that the bone density levels decline with deteriorating metabolic health parameters.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology