Analytical and Clinical Studies on Thyroid Function Tests

在一项合作研究中，我们评估了135名中枢性(二级和三级)甲状腺功能减退患者的各种甲状腺功能测试的诊断性能和临床实用性。不出所料，我们发现，与原发甲状腺功能减退症患者相比，促甲状腺激素(促甲状腺激素)的测定不能用来评估中枢性甲状腺功能减退患者的临床甲状腺状况。用分析合理且经临床验证的方法测定游离甲状腺激素通常是指导这些患者进行左旋甲状腺素替代治疗的可靠方法。在另一项研究中，我们开发了一种新的方法，使用定量研究综合来评估甲状腺激素抑制促甲状腺激素对良性孤立性甲状腺结节的影响。这一方法包括对临床研究和专家意见的系统综述，对选定的介入研究的荟萃分析，对NIH内分泌科医生对假想的良性孤立性甲状腺结节患者的治疗决策的调查，NIH患者接受左旋甲状腺素抑制治疗良性孤立性甲状腺结节的实践验证，以及应用Hills标准评估甲状腺抑制治疗与良性孤立性甲状腺结节消退之间的因果关系。我们的结论是，由于大约四分之一的良性孤立性甲状腺结节患者可能对左旋甲状腺素抑制疗法的临床显著(50%)结节缩小有反应，因此在没有左旋甲状腺素禁忌症的情况下(S)，在所有这些患者中都有必要进行这种疗法的初步试验。在其他正在进行的研究中，我们正在评估甲状腺激素抑制促甲状腺激素在多发性甲状腺肿患者中的临床应用价值，并进一步研究不同采血管对不同非同位素方法测定游离甲状腺激素和促甲状腺激素的影响。

In one collaborative study, we assessed the diagnostic performance and clinical utility of various thyroid function tests in 135 patients with central (secondary and tertiary) hypothyroidism. As expected, we found that, in contrast to patients with pri-mary hypothyroidism, measurement of thyrotropin (thyroid stimulating hormone) cannot be used to assess the clinical thyroid status in central hypothyroid patients. Determination of free thyroxine with analytically sound and clinically validated methods usually was reli-able for guiding levothyroxine replacement therapy in these patients. In another study, we developed a new approach using quantitative research synthesis for assessing the effects of thyrotropin suppression by thyroid hormones on benign solitary thyroid nodules. This approach involved systematic review of the literature for clinical studies and expert opinions, meta-analysis of selected interventional studies, survey of NIH endocrinology practitioners for therapeutic decisions in hypothetical patients with benign solitary thyroid nodule, prac-tice validation in NIH patients treated with levothyroxine suppression for benign solitary thyroid nodules, and application of Hills criteria to assess causality between thyroid sup-pression therapy and regression of benign solitary thyroid nodules. We concluded that since approximately one-quarter of patients with benign solitary thyroid nodule may respond with a clinically significant (>50 percent) reduction in nodule size to levothyroxine suppression therapy, an initial trial of this therapy is warranted in all of these patients in the absence of contraindication(s) to levothyroxine administration. In other studies now in progress we are assessing the clinical utility of thyrotropin sup-pression by thyroid hormones in patients with multinodular goiter, further, we are studying the effects of various blood collection tubes on the measurements of free thyroxine and thyrotropin thyroid stimulating hormone with different non-isotopic methods.