Purpose: To evaluate the usefulness of screening for thyroid dysfunction in various clinical settings.
Design: Review and synthesis of the literature.
Main Results: Screening in the community detects new overt thyrotoxicosis or hypothyroidism in approximately 0.5% of the general population. The yield is best among women over 40 years of age (1%) and is lowest among young men (0%). Case-finding (testing clinic patients who are seeing a physician for unrelated reasons) has a better yield and is less expensive than screening in the community. Patients hospitalized with acute illnesses do not benefit from routine thyroid function testing. However, patients who are admitted to specialized geriatric units because of general disability, failure to thrive, and other indications may benefit. In various studies, from 2% to 5% of patients admitted to geriatric units have treatable thyroid disease. The serum total thyroxine, free thyroxine index, free thyroxine, and sensitive thyrotropin assay are all effective as initial tests for screening. The sensitive thyrotropin assay is less cost-effective than the other choices.
Recommendations: Case-finding in some women over 40 years of age can be useful. Patients admitted to specialized geriatric units may also benefit from routine testing. Thyroid function tests are not indicated for community screening programs or for patients hospitalized with acute medical or psychiatric illnesses.