Characterization of thyroid function in euthyroid and children with subclinical hypothyroidism using a multivariate homeostatic model

Background Subclinical hypothyroidism (SH) is biochemically defined by increased TSH, and normal thyroid hormones and its management is a matter of debate. Herein, we investigated thyroid function in euthyroid and children with SH using published data from population-based curves and a structure parameter inference approach (SPINA) model. Methods The study included 179 children and adolescents with SH and 311 healthy controls. The predicted and calculated secretory capacity of thyroid gland (SPINA-GT) was calculated in all euthyroid children divided into quartiles according to TSH values, and in children with SH, further subcategorized into those with mild SH (TSH: 4.5 – 10 mIU/L) and severe SH (TSH > 10 mIU/L). Results Calculated SPINA-GT values decreased significantly (P < 0.001) from the 1st to the 2nd quartile of normal TSH values in euthyroid children. It was also significantly decreased in mild SH compared to euthyroid children with TSH values within the upper 2 quartiles of TSH range and in severe SH compared to mild SH. Conclusions The implementation of SPINA model for thyroid function gives a wider perspective of thyroid gland’s performance within the euthyroid range of TSH, as well as in SH and add to the discussion for the long-term effects of SH and its management. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee of University Hospital of Patras, Greece approved the protocol. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes