Thyroid function tests. Application of newer methods.

Thyroid function tests are often used to diagnose thyroid disease. Free thyroxine estimates and second- and third-generation assays for serum thyrotropin have simplified and enhanced the accuracy of thyroid function testing. All thyroid function tests have limitations and cannot be used in isolation of the clinical setting. Used appropriately, however, thyroid function tests are an invaluable aid in determining a patient's thyroid status.