Thyroid hormone and the growth plate.

Thyroid hormone was first identified as a potent regulator of skeletal maturation at the growth plate more than forty years ago. Since that time, many in vitro and in vivo studies have confirmed that thyroid hormone regulates the critical transition between cell proliferation and terminal differentiation in the growth plate, specifically the maturation of growth plate chondrocytes into hypertrophic cells. However these studies have neither identified the molecular mechanisms involved in the regulation of skeletal maturation by thyroid hormone, nor demonstrated how the systemic actions of thyroid hormone interface with the local regulatory milieu of the growth plate. This article will review our current understanding of the role of thyroid hormone in regulating the process of endochondral ossification at the growth plate, as well as what is currently known about the molecular mechanisms involved in this regulation.