Hyperthyrotropinemia in relation to endothelial dysfunction in obese adolescents

It has been shown that isolated elevation of thyroid stimulating hormone (hyperthyrotropinemia) is quite frequent in obese adolescents, but it is not clear whether this condition entails an increased risk related to body mass index (BMI).

The aim of the current study was to investigate the relationship between hyperthyrotropinemia and endothelial dysfunction and other cardiovascular risk factors in obese adolescents.

Seventeen obese adolescents with hyperthyrotropinemia (TSH ≥ 4.2 μUI/ml) (group 1), 21 obese adolescents with normal thyroid stimulating hormone (TSH) level (group 2) and 10 age- and sex-matched healthy lean controls were included in the study. Fasting blood glucose (FBG), lipid profile, insulin resistance (HOMA-IR) and thyroid hormones were determined. All participants were subjected to ultrasound recording of brachial artery diameter at rest and after reactive hyperemia (FMD) for assessment of endothelial function.

BMI and free triiodothyronine (fT3) levels were higher in obese adolescents with hyperthyrotropinemia (group 1) than in those with normal TSH (group 2) (p < 0.05), but there were no significant differences between the two groups in other metabolic parameters (lipid profile and HOMA-IR). The FMD was significantly low in obese adolescents (groups 1 and 2) relative to controls (3.4 ± 18% in group 1 and 3.6 ± 2.2% in group 2 vs. 10.4 ± 3.1% in control subjects), but there was no statistical difference between obese adolescents with hyperthyrotropinemia (group 1) and those with normal TSH (group 2). There were positive correlations between TSH and BMI (p = 0.03) and between fT3 and BMI (p = 0.04), but no correlation between TSH and lipid profile, HOMA-IR or FMD.

Hyperthyrotropinemia is not related to endothelial dysfunction or metabolic risk factors in obese adolescents.