Subclinical hypothyroidism in obese children and metabolic implications
G. Genoni, F. Prodam, S. Parlamento, C. Balossini, E. Pozzi, R. Ricotti, V. Agarla, S. Bellone & G. Bona
Introduction: Aim of this study was to assess the prevalence of subclinical hypothyroidism in a paediatric population of overweight and obese children and its association with metabolic parameters and with metabolic syndrome (MS).
Subjects and methods: Clinical and metabolic evaluations in 600 overweight and obese children and adolescents (310 females, 290 males, 260 prepubertal, 240 pubertal, mean age: 10.7±3.1 years) were performed. MS was defined according to paediatric NCEP-ATPIII criteria. TSH levels were evaluated both in quartiles and according to a fixed cut-off level (pathological value >3.500 μUl/ml). The presence of autoimmune thyroiditis was assessed in those subjects with abnormal TSH values.
Results: 75 subjects (12.5%) had abnormal TSH levels and 10 of them (13.3%) showed antithyroid antibodies. Age decreased (P<0.0001) and the number of prepubertal children increased (P<0.006) with the rise of TSH levels. non-HDL cholesterol (P<0.03), triglycerides (P<0.0001), PNFI index (P<0.0001), fasting glucose (P<0.04), HOMA-IR (P<0.04), glucose peak (P<0.03) and glucose area (P<0.01) during OGTT increased with the rise of TSH levels. No differences in the prevalence of MS were found among the TSH quartiles and in subjects with altered TSH levels. A negative correlation between age and TSH levels was found (β=−0.122; P<0.003). Furthermore a positive correlation between TSH and non-HDL cholesterol (β=0.095; P<0.02), triglycerides (β=0.232; P<0.0001), PNFI (β=0.185; P<0.0001) and fasting glucose (β=0.107; P<0.01) was shown independently of confounding factors.
Conclusions: Subclinical hypothyroidism and autoimmune thyroiditis are frequent in overweight and obese children. The association between TSH levels and metabolic parameters suggests a role of the hypothalamuspituitarythyroid axis in the regulation of lipids and glucose metabolism. Conversely the absence of an association with the metabolic syndrome suggests that this axis may modulate specific metabolic alterations.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.