Physiological Effects of Thyroid Hormones

PHYSIOLOGICAL EFFECTS OF THYROID HORMONES

There is no discrete target tissue for thyroid hormones; virtually every cell in the body is affected by thyroid hormones in some way. These hormones are intimately involved in the maintenance of normal function in vir-tually every cell type, including cellular responsiveness to other hormones, to the availability of metabolic sub-strates, to growth factors, and so on. Thyroid dysfunc-tion can produce dramatic changes in the metabolism of proteins, carbohydrates, and lipids at the cellular level that can have repercussions for the operation of the cardiovascular, gastrointestinal, musculoskeletal, reproductive, and nervous systems. Some of the clinical manifestations of thyroid dysfunction are presented next in the discussions of hypothyroid and hyperthy-roid states.