Growth in Children with Thyroid Dysfunction

Thyroid hormones (TH) are critical for early brain development, somatic growth, and bone and pubertal maturation. Moreover, they are crucial for survival, both in rodents and humans. In many respects, (TH) may be viewed as tissue growth factors. Effects on growth and development are classified as genomic actions mediated via stimulation of mRNA for pituitary growth hormone (GH) synthesis, secretion and sensitivity. TH potentiate GH stimulation of the synthesis and action of insulin-like growth factor 1 (IGF1) and stimula‐ tion of the production of different growth factors (epidermal growth factor, nerve growth factor, and erythropoietin). Cartilage response to IGF1 and osteoblastic/osteoclastic bone remodeling are also regulated by thyroid hormones. Unlike insulin and cortisol levels, which fluctuate widely in response to food ingestion and stress, thyroid hormones are typically maintained at a constant level that keeps the metabolic machinery functioning at a proper rate (Zimmerman-Belsing et al., 2003).