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Subclinical thyroid dysfunction is a common clinical problem with many controversial issues regarding screening, evaluation, and management. Subclinical hypothyroidism is defined as high levels of serum thyrotropin (thyroid-stimulating hormone or TSH) associated with normal levels of total or free thyroxine (T4) and triiodothyronine (T3). The overall prevalence is 4% to 10% in the general population and up to 20% in women older than 60 years. Several alternative labels have been proposed to describe this condition and include "compensated hypothyroidism," "preclinical hypothyroidism," "mild thyroid failure," and "mild hypothyroidism." Although each term has subtle implications that may be more or less appropriate in various circumstances, we will use the term "subclinical hypothyroidism" in the interest of consistency with a recent publication that is the topic of this discussion. Subclinical hyperthyroidism is defined as low levels of serum TSH associated with normal levels of free T4 and free T3. The prevalence of this condition is about 2%, being more common in women, in blacks, and in the elderly population.
To develop an evidence-based approach to the various unresolved clinical issues regarding subclinical thyroid disease, the American Association of Clinical Endocrinologists (AACE), the American Thyroid Association (ATA), and The Endocrine Society (TES) jointly sponsored a Consensus Development Conference, which was held in September 2002. Several questions were presented to a panel of 13 experts, including 8 experts in thyroid disease; the other 5 panel members had expertise in cardiology, epidemiology, biostatistics, evidence-based medicine (EBM), health-services research, general internal medicine, and clinical nutrition. The consensus panel report was the result of an extensive review of the published literature on these topics available at the time. The conference participants meticulously followed the principles of EBM to summarize all existing pertinent data and to make EBM recommendations on the controversial issues of screening, evaluation, and management of patients with subclinical thyroid disease. The recently published consensus panel's conclusions and recommendations were developed independently and therefore did not necessitate official review or approval by the three sponsoring organizations. Recognizing that EBM methodology cannot thoroughly address gray areas where existing evidence is inadequate and that EBM-derived guidelines cannot specifically address the multitude of variations encountered by clinicians in their management of individual patients, the consensus authors also published an accompanying case-based discussion to illustrate how the guidelines could be applied in several patient scenarios. The authors of these two outstanding articles are to be congratulated for these excellent publications and thanked for their service to the community of health-care providers who are responsible for the management of patients with thyroid disorders.
Subsequently, having carefully studied the consensus conference data, summaries, and recommendations, the leadership of AACE, ATA, and TES determined that it would not be appropriate for practicing clinicians and the regulatory elements of the health-care industry to be given the impression that the membership of these 3 organizations unanimously agreed with all consensus conference recommendations, despite their sponsorship of the conference itself. They believed that the data in several areas were inconclusive and that further alternative interpretations and recommendations were not only reasonable but also warranted in the interest of academic fairness. Therefore, two members from each of these respective organizations were invited to form a panel to review the consensus conference recommendations to determine whether there were areas of legitimate and substantial disagreement. All members of this panel (the authors of the current report) are regularly involved in the clinical care of patients with thyroid disease, and all have previously published literature in the thyroid field, although not necessarily on the topic of subclinical thyroid disease. The participants were not chosen specifically for their views on subclinical thyroid disease but rather to represent the membership of the 3 organizations.
Panel members were or became thoroughly familiar with the body of literature that provided the data on which the consensus conference recommendations were based. They did not conduct an independent data analysis. Instead, they relied on the existing data presentation from the consensus conference and offered their own alternative interpretations, conclusions, and recommendations that they believed were warranted on the basis of the strength of the evidence presented by the consensus conference and their own extensive clinical experience. The present opinion paper was then submitted to the leadership of each of the 3 organizations (AACE, ATA, and TES), who presented it to each of their governing bodies, which made further recommendations and then endorsed it in its current form as a reasonable alternative and an appropriate response, not to refute but to provide a counterbalance to the recommendations made by the consensus conference.
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