The second disturbing issue in the USPSTF statement is the use of the term “asymptomatic” in the context of thyroid dysfunction. By definition, a patient with symptoms of fatigue, hair loss, or palpitations who has a TSH test done is undergoing “case finding,” not screening. It is hard to justify withholding TSH testing in a patient who does not have an obvious alternative cause for any of these symptoms. The clinical conundrum arises when a patient with any of the nonspecific symptoms of thyroid dysfunction has test results consistent with subclinical thyroid dysfunction. Were the patient's symptoms due to a mild thyroid problem, or is there an unrelated biochemical abnormality that may or may not be clinically significant? The effectiveness of treatment of either type of subclinical thyroid dysfunction in reversing the symptoms that triggered testing has never been evaluated in placebo-controlled trials. Therefore, it is not clear that the
management of a symptomatic patient with subclinical thyroid dysfunction should differ from that of an asymptomatic patient, given the potential for beneficial effects on cardiovascular outcomes and bone health, which might occur with therapy even in asymptomatic persons.