The serum thyroid stimulating hormone (TSH) assay is a common blood test that is already covered by the Medicare program for the diagnosis and treatment of illness. This report is an inquiry into the additional costs and benefits of also offering this test as a preventive service.
Thyroid dysfunction is common, especially in elderly people. While it is accepted that treatment will benefit patients who present with significant symptoms or complications, it difficult to determine whether treatment would provide significant net benefit in persons who have abnormal TSH levels but little evidence of illness; the potential for harm is similar but potential for benefit is less.
These uncertainties make it difficult to assess the value of a screening program for thyroid dysfunction. The serum TSH test is reliable, valid, and acceptable to patients. The diagnosis of thyroid dysfunction can usually be made definitively. However, the natural history is not highly predictable; a large proportion of subjects screened who have positive test results will not develop significant morbidity from thyroid dysfunction. Available treatments can improve biochemical and physiological indications of thyroid dysfunction, but there are no studies of treatment of subjects identified through screening that show significant benefits from treatment in terms of improved survival, function, or quality of life. Treatment begun at the time of screening also has not been demonstrated to provide benefits greater than treatment initiated when the disease is clinically manifest.
The Committee estimated that a relatively small number of Medicare beneficiaries would take advantage of a serum TSH screening benefit and found a widespread lack of information necessary to make a meaningful assessment of the true economic costs of screening.