The impact of thyroid function on the occurrence of metabolic syndrome in obese children and adolescents

Introduction
Thyroid axis abnormalities are common in obese patients. Their contribution in the development of metabolic obesity complications remains unclear.

Aim of study
To assess the influence of thyroid axis dysfunction on the occurrence of metabolic obesity complications.

Material and methods
A cross-sectional review of the thyroid function in 100 obese patients (59 girls and 41 boys, mean age 13.5 years) with alimentary obe-sity (mean standardised body mass index [BMI SDS] in boys 4.175 and girls 4.723) complicated by metabolic syndrome (MS) diag-nosed on the basis of the IDF 2006 criteria (MS, 25 patients) and uncomplicated (75 patients). TSH, fT4, fT3 thyroid peroxidase anti-bodies (TPOAb), and thyroglobulin antibodies (TGAb) were assessed in a single fasting blood sample.

Results
There was no case of overt thyroid disease within the whole analysed group. There were no significant differences in mean TSH, fT4, and fT3 levels in patients with and without MS (2.7 µIU/ml vs. 3.0 µIU/ml, 14.5 vs. 14.0 pmol/l, and 5.6 vs. 6.2, respectively; p > 0.05). In the MS group only two patients (8%) presented with a TSH level above the upper limit of the normal range; in the group without MS elevated TSH was noticed in 18 (24%) patients. The maximal value of TSH (10.44 µIU/ml) was noticed in one boy without MS. Positive TPOAb and/or TGAb were present in 11% of all patients: two patients (8%) with MS and nine (12%) without MS.

Conclusions
Isolated increased TSH level is common in obese adolescents, although there is no correlation between TSH, fT3, and fT4 levels and BMI SDS value. Isolated increased TSH level is not associated with the occurrence of MS in obese adolescents. The occurrence of asymptomatic autoimmune thyroiditis (AITD) in obese adolescents is more common than in the general population.