Early appearance of thyroid autoimmunity in children followed from birth for type 1 diabetes risk

Jonsdottir B; Clasen JL; Vehik K; Lernmark AE; Lundgren M; Bonifacio E; Schatz D; Ziegler AG; Hagopian W; Rewers M; McIndoe R; Toppari J; Krischer J; Akolkar B; Steck A; Veijola R; Haller MJ; H; TEDDY Study Group Elding Larsson

doi:10.1530/ey.22.3.10

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ESPE Yearbook of Paediatric Endocrinology (2025) 22 3.10 | DOI: 10.1530/ey.22.3.10

ESPEYB25 3. Thyroid Auto-Immune Thyroid Disease (4 abstracts)

3.10. Early appearance of thyroid autoimmunity in children followed from birth for type 1 diabetes risk

Jonsdottir B , Clasen JL , Vehik K , Lernmark Æ , Lundgren M , Bonifacio E , Schatz D , Ziegler AG , Hagopian W , Rewers M , McIndoe R , Toppari J , Krischer J , Akolkar B , Steck A , Veijola R , Haller MJ & Elding Larsson H; TEDDY Study Group

J Clin Endocrinol Metab. 2025 Jan 21;110(2):498-510. doi: 10.1210/clinem/dgae478. PMID: 38996042

Brief Summary: This prospective cohort study from the TEDDY project followed 5,066 children with increased genetic risk for type 1 diabetes from birth through adolescence. It found that thyroid autoantibodies (TPOAb and/or TgAb) emerge as early as 10–15 months of age, with simultaneous seroconversion significantly increasing the risk of clinical thyroid disease.

The findings challenge the conventional view that autoimmune thyroid disease (AITD) is a later-onset condition by demonstrating that thyroid autoimmunity may begin well before school age in genetically at-risk children. A notable observation was the strong sex difference: girls had more than double the risk of developing thyroid autoimmunity compared to boys, even in early childhood, contrasting with previous reports suggesting minimal sex differences before puberty. A family history of AITD, particularly paternal, further increased risk, underscoring the roles of both sex and heritability.

Children who developed both TPOAb and TgAb simultaneously had a markedly higher risk of clinical thyroid disease (hazard ratio = 6.34) than those with single antibody positivity. Notably, the timing of simultaneous seroconversion was a stronger predictor of disease progression than the order in which antibodies appeared.

In the context of increasing autoimmune comorbidities among children, especially those at risk for type 1 diabetes, these findings support earlier and broader thyroid screening strategies in genetically susceptible populations. Early detection of thyroid autoimmunity could enable closer monitoring and timely intervention, potentially preventing complications such as growth retardation or cognitive deficits.

This study significantly advances our understanding of the early natural history and risk factors for AITD and highlights the importance of sex-specific and family history–guided surveillance in pediatric endocrinology.