Contemporary approach to thyroid disease emphasizing use of high-sensitivity thyrotropin assays

Capabilities of new high-sensitivity immunoradiometric assays for thyroid-stimulating hormone (TSH-IRMA) to distinguish among hypothyroid, euthyroid, and hyperthyroid subjects and patient groups with low TSH for nonthyroidal causes suggested an algorithmic approach (directed TSH) to the evaluation of patients with suspected thyroid disease. Utilizing the algorithm, a TSH-IRMA result outside normal limits (0.5 to 5.0 mU/L) generates follow-up tests on the same sample. The interpretation of thyroid function tests (TSH-IRMA, thyroxine, resin uptake, free thyroxine index) and associated studies in the context of different clinical settings is reviewed. The approach is a cost-effective and efficient utilization of laboratory services.