Unusual manifestations of hypothyroidism.

Thyroid hormone exerts direct effects on essentially all of the organ systems of the body. Hypothyroidism is a frequently diagnosed endocrine disorder that has characteristic clinical signs and symptoms. In addition to these common manifestations, however, there are many additional manifestations of hypothyroidism that are less commonly acknowledged and include involvement of the hematologic, muscular, cardiac, and rheumatologic systems. It is important to recognize that these other organ systems may be involved and that the resulting disease states can dominate the clinical picture. As with the classic manifestations of hypothyroidism, these unusual manifestations respond to thyroid hormone replacement therapy. Thus, the importance of recognizing these signs and symptoms, as a result of hypothyroidism, is evident. This article emphasizes these less common manifestations of the patient with hypothyroidism, and, in addition, discusses the possible pathophysiologic mechanisms by which thyroid hormone deficiency can lead to organ system dysfunction.