How do thyroid hormones influence growth of the brain and skeleton?

Thyroid hormones, specifically triiodothyronine, are essential for the normal growth and development of the brain and skeleton, particularly during fetal life and infancy.1

Influence on Brain and Skeletal Growth

• General Mechanism: Thyroid hormones facilitate growth and skeletal maturation primarily through their broad effects on cell metabolism. They regulate the transcription of various genes, influencing the synthesis of proteins necessary for cellular function and development.23
• Skeletal Development: Thyroid hormones are critical for bone growth and maturation. A deficiency in these hormones leads to a retardation of skeletal growth and development, often resulting in delayed bone age. Conversely, an excess of thyroid hormone in the young can cause the premature appearance of ossification centers and the early closure of the epiphyses, which can ultimately impact final stature.24
• Brain Development: During the prenatal and early postnatal periods, thyroid hormones are vital for normal neural development. Insufficient levels of these hormones during these critical windows can lead to significant developmental issues, including intellectual disability and conditions such as dwarfism.15