Thyroid dysfunction in the severely ill and elderly

Manifestations of thyrotoxicosis and hypothyroidism are often ill-defined in elderly and seriously ill patients, and signs and symptoms may suggest a nonendocrine disease process instead. It is vitally important that physicians be aware of the possibility of thyroid disease in such patients. Failure to suspect the diagnosis may result in improper treatment and use of invasive diagnostic tests that not only fail to yield helpful results but also are potentially detrimental to the outcome. It is also essential to be able to distinguish between test abnormalities that indicate primary thyroid dysfunction and those that reveal an adaptive response to nonthyroidal illness.