ABSTRACT
Background: Despite being the most performed laboratory endocrine investigation, the optimum use of thyroid tests (thyrotropin [TSH] and thyroid hormone [TH] measurement) is open to question and the interpretation of the results from these tests can be ambiguous. The American Thyroid Association (ATA) with its expertise support the endeavor of the U.S. Centers for Disease Control (CDC) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve and maintain standardization and harmonization of thyroid testing. ATA mandated an international interdisciplinary working group panel to survey the status of thyroid testing by reviewing the recent literature to revise or update the criteria as needed in mutual agreement and to inform clinical care. Summary: This review represents the conclusions on the clinical use of current routine TSH and TH (thyroxine [T4] and triiodothyronine [T3]) assays, taking into account geographic differences in disease prevalence and clinical and laboratory practice among writing members. The interaction between physiological, pathophysiological, and pharmacological factors and thyroid assays can affect their measurements and confound result interpretation. These factors need to be considered in the clinical context of the patient for appropriate test ordering and result interpretation. Despite significant advances in laboratory methods over the past 50 years, routine thyroid assays remain susceptible to idiosyncratic analytical interference that may produce spurious results. Improved standardization needs to be demonstrated through ongoing international efforts before results from different assays can be considered equivalent. Emerging technology (e.g., mass spectrometry) shows promise for improved analytical performance, but more evidence of its clinical utility and improved throughput is required before it can be considered for routine use. Close clinical-laboratory collaboration is encouraged to overcome and avoid the pitfalls in thyroid testing as well as resolve clinically discrepant results. The evidence base supporting the conclusions of this review is summarized in four detailed online technical supplements. Conclusions: Over the past five decades, testing for TSH, T4, and T3 has evolved from manual radioisotopic immunoassays to nonisotopic multiplexed immunometric assays using highly automated equipment. Despite these technical advances, physicians and laboratorians performing these analyses must understand limitations of these methods to properly order tests and interpret results.
Subject(s)
Thyroxine , Triiodothyronine , Humans , Thyroid Gland , Thyrotropin , Thyroid HormonesABSTRACT
Background: The 2015 American Thyroid Association (ATA) clinical practice guidelines (CPGs) on management of thyroid nodules (TNs) and differentiated thyroid cancer (DTC) in adults were developed to inform clinicians, patients, researchers, and health policy makers about the best available evidence, and its limitations, relating to management of these conditions. Methods: We conducted a cross-sectional electronic survey of ATA members' perspectives of these CPGs, using a standardized survey (Clinician Guidelines Determinant Questionnaire) developed by the Guidelines International Network. A survey link was electronically mailed to members in February of 2019, with reminders sent to nonrespondents 2 and 5 weeks later. Data were descriptively summarized, after excluding missing responses. Results: The overall response rate was 19.8% (348/1761). The effective response rate was 20.2% (348/1720), after excluding a recently deceased member and individuals who had either invalid e-mail addresses or whose e-mails were returned. Of the respondents, 37.9% (132/348) were female, 60.4% (209/346) were endocrinologists, 27.5% (95/346) were surgeons, and 3.5% (12/346) were nuclear medicine specialists. The majority of respondents (71.9%; 250/348) were at a mid- or advanced-career level, and more than half were in academia (57.5%; 195/339). The majority (69.8%; 243/348) practiced in North America. The vast majority of respondents indicated that the CPGs explained the underlying evidence (92.3%; 298/323) and 92.9% (300/323) agreed or strongly agreed with the content. Most respondents stated that they regularly used the CPGs in their practice (83.0%; 268/323). Most respondents (83.0%; 268/323) also agreed or strongly agreed that the recommendations were easy to incorporate in their practice. The most popular CPG format was an electronic desktop file (78.8%; 252/320). Shorter more frequent CPGs were favored by 55.0% (176/320) of respondents, and longer traditional CPGs were favored by 39.7% (127/320). Conclusions: The clinical content and evidence explanations in the adult TN and DTC CPGs are widely accepted and applied among ATA survey respondents. Future ATA CPG updates need to be optimized to best meet users' preferences regarding format, frequency, and length.
