Pituitary response to thyrotropin releasing hormone in children with overweight and obesity.

Thyroid stimulating hormone (TSH) concentrations in the high normal range are common in children with overweight and obesity, and associated with increased cardiovascular disease risk. Prior studies aiming at unravelling the mechanisms underlying these high TSH concentrations mainly focused on factors promoting thyrotropin releasing hormone (TRH) production as a cause for high TSH concentrations. However, it is unknown whether TSH release of the pituitary in response to TRH is affected in children with overweight and obesity. Here we describe TSH release of the pituitary in response to exogenous TRH in 73 euthyroid children (39% males) with overweight or (morbid) obesity. Baseline TSH concentrations (0.9-5.5 mU/L) were not associated with BMI z score, whereas these concentrations were positively associated with TSH concentrations 20 minutes after TRH administration (r(2) = 0.484, p < 0.001) and the TSH incremental area under the curve during the TRH stimulation test (r(2) = 0.307, p < 0.001). These results suggest that pituitary TSH release in response to TRH stimulation might be an important factor contributing to high normal serum TSH concentrations, which is a regular finding in children with overweight and obesity. The clinical significance and the intermediate factors contributing to pituitary TSH release need to be elucidated in future studies.