The Relationship Between TSH and Free T4 in a Large Population Is Complex and Nonlinear and Differs by Age and Sex
The Relationship Between TSH and Free T4 in a Large Population Is Complex and Nonlinear and Differs by Age and Sex
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DOI：
10.1210/jc.2012-4223
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发表时间：
2013-07-01
影响因子：
5.8
通讯作者：
Walsh, John P.
中科院分区：
文献类型：
--
作者：
Hadlow, Narelle C.;Rothacker, Karen M.;Walsh, John P.
背景：TSH和T-4之间的关系被认为是反对数线性的，但最近的研究对此提出了质疑。有关于年龄和性别差异在TSH-T-4 relationships.Objective：本研究的目的是评估TSH-游离T-4 relationship in a large sampling.Methods：在一项横断面回顾性研究中，我们分析了TSH和游离T4结果从152 261名受试者收集了超过12年由一个单一的实验室。对于每一个游离T-4值（皮摩尔/升），TSH的中位数计算和分析的性别和年龄（在20岁的波段）。数学模型证实，在游离T-4浓度为7和21 pmol/L时，它由两条S形曲线描述，曲线上有两个点。对于游离T4在参考范围内（10-20 pmol/L），男性中位TSH高于女性（P < .001），并且在80岁及以上的年龄段中最高（P < .001）。相反，在明显的甲状腺功能减退症（n = 4403），TSH是较低的年龄组比那些年龄在20-39岁（P < .001）。结论：TSH游离T-4的关系不是反对数线性，但可以描述为2个重叠的负S形曲线。在生理游离T-4浓度下，男性和老年人的TSH较高，而年轻人对甲状腺功能减退的TSH反应更强烈。这些结果促进了对TSH-游离T-4关系的理解，这对甲状腺病理生理学和甲状腺疾病的实验室诊断至关重要。
Context: The relationship between TSH and T-4 is thought to be inverse log-linear, but recent studies have challenged this. There are limited data regarding age and sex differences in the TSH-T-4 relationship.Objective: The purpose of this study was to evaluate the TSH-free T-4 relationship in a large sample.Methods: In a cross-sectional, retrospective study, we analyzed TSH and free T4 results from 152 261 subjects collected over 12 years by a single laboratory. For each free T-4 value (in picomoles per liter), the median TSH was calculated and analyzed by sex and age (in 20-year bands).Results: The relationship between log TSH and free T-4 was nonlinear. Mathematical modeling confirmed that it was described by 2 sigmoid curves with inflexion points at free T-4 concentrations of 7 and 21 pmol/L. For free T4 within the reference range (10-20 pmol/L), median TSH was higher in men than in women (P < .001) and increased across age bands with the highest values in those 80 years and older (P < .001). In contrast, in overt hypothyroidism (n = 4403), TSH was lower in older age groups than in those aged 20-39 years (P < .001).Conclusions: The TSH-free T-4 relationship is not inverse log-linear but can be described by 2 overlapping negative sigmoid curves. At physiological free T-4 concentrations, TSH is higher in men and in older people, whereas the TSH response to hypothyroidism is more robust in younger people. These results advance understanding of the TSH-free T-4 relationship, which is central to thyroid pathophysiology and laboratory diagnosis of thyroid disease.