THYROID-FUNCTION TESTS - PERFORMANCE AND LIMITATIONS OF CURRENT METHODOLOGIES

An assessment of existing laboratory procedures for measuring thyroid function is warranted because recent methodological advances, which include improved analytical sensitivity and accuracy and, as a consequence of automation, better precision, have had an impact on thyroid function testing. It is important that the still remaining technical limitations of assays of thyroid hormones and thyrotropin (TSH) in Serum be understood by the clinical pathologists and chemists selecting the methods, and by the clinicians responsible for the diagnostic and ultimate therapeutic decisions. Methodological performance characteristics, capacity requirements, economical aspects-important in the current environment of rising costs and tight budgets-and the prevalence of thyroid diseases and other conditions affecting thyroid-related analytes should be considered when selecting for clinical-service laboratories thyroid hormone and TSH assays from the large number of alternatives now available. The opinions on analytical methods expressed in this editorial review are based largely on the experience of this author. Criteria for the use of thyroid function tests in different clinical settings have been discussed in a recent report by a committee of the American Thyroid Association [1]. Readers are also referred to an article on medical needs in the evaluation of thyroid function, including the need for Screening programmes, by Lindstedt [2].