Early thyroxine treatment in Down syndrome and thyroid function later in life

Area of Science:

• Endocrinology
• Pediatrics
• Genetics

Background:

• The hypothalamus-pituitary-thyroid (HPT) axis set point is established early in life.
• Children with Down syndrome are at increased risk for autoimmune thyroiditis.
• Early life interventions may impact HPT axis development and thyroid health.

Purpose of the Study:

• To investigate the long-term effects of early thyroxine treatment on the HPT axis set point in children with Down syndrome.
• To assess the influence of early thyroxine treatment on the development of autoimmune thyroiditis in this population.

Main Methods:

• A randomized controlled trial (RCT) follow-up study included 123 children with Down syndrome.
• Thyroid function tests (TSH, FT4) and ultrasound were performed 8.7 years post-RCT.
• Analysis focused on 71 children not on thyroid medication and without autoimmune thyroiditis.

Main Results:

• Thyroxine-treated children had significantly higher FT4 levels (14.1 vs 13.0 pmol/L) nearly 9 years later.
• Anti-TPO positivity increased with age, with a lower percentage in the thyroxine group (18.5% vs 32%).
• Thyroid volume was significantly lower than reference values and similar between groups.

Conclusions:

• Early thyroxine treatment may lead to a sustained mild increase in FT4 and influence the maturing HPT axis set point.
• A trend suggests early thyroxine treatment may offer protection against developing thyroid autoimmunity.
• Low thyroid volume in children with Down syndrome may indicate Down-specific thyroid hypoplasia.