Department of Medicine, Washington Hospital Center, and Georgetown University School of Medicine, Building D, Suite 232, 4000 Reservoir Road, Washington, DC 20007, USA. adlers@georgetown.edu
 

This article briefly summarizes thyroid function alterations generally seen in the euthyroid sick syndrome, provides an overview of specific thyroidal adaptations during several clinical conditions and secondary to specific pharmacologic agents, and discusses the current controversy in thyroid hormone treatment of nonthyroidal illness.