Chen Xinxin, Zhou Yulin, Zhou Mengxi, Yin Qinglei, Wang Shu
Shanghai Clinical Center for Endocrine and Metabolic Diseases, Department of Endocrinology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, China.
Int J Endocrinol. 2018 Jun 4;2018:4836736. doi: 10.1155/2018/4836736. eCollection 2018.
The results of previous studies on the usefulness of free triiodothyronine (FT3) to free thyroxine (FT4) are controversial. We investigated the usefulness of FT3, FT4, and FT3/FT4 ratio in differentiating Graves' disease (GD) from destructive thyroiditis.
A total of 126 patients with untreated GD, 36 with painless thyroiditis, 18 with painful subacute thyroiditis, and 63 healthy controls, were recruited. The levels of FT3 and FT4 and the FT3/FT4 ratios for the different etiologies of thyrotoxicosis were evaluated separately by receiver operating characteristic (ROC) curve analysis. The expression levels of type 1 and type 2 deiodinase ( and ) in thyroid tissues were also investigated.
The optimal cut-off values were 7.215 pmol/L for FT3, 21.71 pmol/L for FT4, and 0.4056 for the FT3/FT4 ratio. The specificity and positive predictive value of the FT3/FT4 ratio were highest for values > 0.4056. mRNA expression was significantly higher in the thyroid tissue of patients with GD ( = 0.013).
We demonstrated that the FT3/FT4 ratio was useful in differentiating GD from destructive thyroiditis. In addition, a relatively high expression of type 1 deiodinase in the thyroid might be responsible for the high FT3/FT4 ratio in patients with GD.
既往关于游离三碘甲状腺原氨酸（FT3）与游离甲状腺素（FT4）效用的研究结果存在争议。我们研究了FT3、FT4及FT3/FT4比值在鉴别格雷夫斯病（GD）与破坏性甲状腺炎中的效用。
共纳入126例未经治疗的GD患者、36例无痛性甲状腺炎患者、18例疼痛性亚急性甲状腺炎患者及63例健康对照者。通过受试者工作特征（ROC）曲线分析分别评估不同病因甲状腺毒症患者的FT3、FT4水平及FT3/FT4比值。同时研究甲状腺组织中1型和2型脱碘酶（和）的表达水平。
FT3的最佳截断值为7.215 pmol/L，FT4为21.71 pmol/L，FT3/FT4比值为0.4056。FT3/FT4比值>0.4056时，其特异性和阳性预测值最高。GD患者甲状腺组织中的mRNA表达显著更高（=0.013）。
我们证明FT3/FT4比值有助于鉴别GD与破坏性甲状腺炎。此外，甲状腺中相对较高的1型脱碘酶表达可能是GD患者FT3/FT4比值升高的原因。
