Objective Thyroid hormones are essential for normal brain development. The aim of this study is to assess if high concentration of thyroid stimulating hormone (TSH) that is below the clinical threshold (5–15 mIU/L) at neonatal screening is linked to psychomotor development impairments in the offspring at preschool age.
Design A total of 284 Belgian preschool children 4–6 years old and their mothers were included in the study. The children were randomly selected from the total list of neonates screened in 2008, 2009 and 2010 by the Brussels newborn screening centre. The sampling was stratified by gender and TSH range (0.45–15 mIU/L). Infants with congenital hypothyroidism (>15 mIU/L), low birth weight and/or prematurity were excluded. Psychomotor development was assessed using the Charlop-Atwell scale of motor coordination. The iodine status of children was determined using median urinary iodine concentration. Socioeconomic, parental and child potential confounding factors were measured through a self-administered questionnaire.
Results TSH level was not significantly associated with total motor score (average change in z-score per unit increase in TSH is 0.02 (−0.03, 0.07), p=0.351), objective motor score (p=0.794) and subjective motor score (p=0.124). No significant associations were found using multivariate regression model to control confounding factors.
Conclusions Mild thyroid dysfunction in the newborn—reflected by an elevation of TSH that is below the clinical threshold (5–15 mIU/L)—was not associated with impaired psychomotor development at preschool age.
- psychomotor development
- thyroid-stimulating hormone
- preschool children
- iodine deficiency
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Contributors All authors contributed to the conception and the design of the study, the data interpretation, and the revision of the article. CT wrote the manuscript, performed the data collection and the data analysis. All authors helped in the interpretation of the results and helped to write the manuscript. All the authors approved the final version of the article.
Funding The ‘Fonds de la Recherche Scientifique Medicale’ (Grant number: 3.4572.11) and the ‘Belgian Federal Science Policy Office’.
Competing interests None declared.
Patient consent Parental/guardian consent obtained.
Ethics approval The study protocol and consent form were approved by the Ethical Committee of the Erasmus hospital (Université Libre de Bruxelles, Brussels) in accordance with the Code of Ethics of the World Medical Association for experiments involving humans (Declaration of Helsinki). This study was also approved by the Belgian Commission for the Protection of the Privacy Reference: RN29/2012.
Provenance and peer review Not commissioned; externally peer reviewed.
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