Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Spain.
Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Spain; Institut d'Investigació Sanitària de les Illes Balears (IdISBa), Spain.
Clin Chim Acta. 2020 Jun;505:125-129. doi: 10.1016/j.cca.2020.02.016. Epub 2020 Feb 15.
BACKGROUND-AIM: Measurement of serum thyrotropin is currently the recommended test for the screening of thyroid dysfunction, while serum free thyroxine is kept as a reflex test. In our laboratory, the strategy followed in adult individuals from Primary Care includes a 'safety margin' for requests with a thyrotropin ≤1.0 or ≥4.0 mIU/L (normal: 0.35-4.95 mIU/L). Our aim was to optimize the thyrotropin cut-off values for the addition of free thyroxine and, based on these cut-offs, to retrospectively analyze avoidable free thyroxine measurements and possible adverse clinical consequences.
Retrospective observational study performed in a tertiary care hospital between 2013 and 2018. We considered all laboratory requests for screening of thyroid dysfunction (TD) in adult patients from Primary Care. Requests from patients with a previous diagnosis of thyroid disease or pregnant women were excluded. Different receiver operating characteristic (ROC) curves were performed and the obtained thyrotropin cut-off values were compared. Economic savings were assessed considering the current cost of free thyroxin assays in our laboratory.
From a total of 554,529 TD protocols included, 119,504 requests had free thyroxine added. From the ROC curve that enables ≥95% of abnormal free thyroxine results to be detected, the thyrotropin values obtained were ≥4.58 mIU/L and ≤0.94 mIU/L. These thyrotropin cut-off values would lead to a saving of 22.7% of annual free thyroxine measurements without adverse clinical consequences.
Setting optimized thyrotropin cutoffs for reflex testing of free thyroxine would reduce the need for this test. Clinical laboratories need to offer not only true results, but also become the cornerstone in the optimization of resources.
背景-目的：目前，血清促甲状腺激素的检测被推荐用于甲状腺功能障碍的筛查，而血清游离甲状腺素则作为一种反射性检测。在我们的实验室中，对初级保健成人个体遵循的策略包括促甲状腺激素≤1.0 或≥4.0 mIU/L（正常值：0.35-4.95 mIU/L）时的“安全余量”。我们的目的是优化促甲状腺激素的截止值，以添加游离甲状腺素，并根据这些截止值回顾性分析可避免的游离甲状腺素检测和可能的不良临床后果。
在 2013 年至 2018 年期间，我们在一家三级保健医院进行了一项回顾性观察性研究。我们考虑了所有来自初级保健的甲状腺功能障碍（TD）筛查的实验室请求。排除了患有甲状腺疾病或孕妇的患者的请求。进行了不同的接收者操作特征（ROC）曲线，并比较了获得的促甲状腺激素截止值。考虑到我们实验室当前游离甲状腺素检测的成本，评估了经济节省。
从总共纳入的 554,529 例 TD 方案中，有 119,504 例请求添加了游离甲状腺素。从能够检测到≥95%异常游离甲状腺素结果的 ROC 曲线中，获得的促甲状腺激素值分别为≥4.58 mIU/L 和≤0.94 mIU/L。这些促甲状腺激素截止值将导致每年游离甲状腺素检测量减少 22.7%，而不会产生不良临床后果。
为游离甲状腺素的反射性检测设定优化的促甲状腺激素截止值将减少对该检测的需求。临床实验室不仅需要提供真实的结果，还需要成为优化资源的基石。
