McIver B, Gorman C A
Division of Endocrinology and Metabolism, Mayo Clinic, Rochester, Minnesota 55905, USA.
Thyroid. 1997 Feb;7(1):125-32. doi: 10.1089/thy.1997.7.125.
Abnormalities of thyroid hormone concentrations are seen commonly in a wide variety of nonthyroidal illnesses, resulting in low triiodothyronine, total thyroxine, and thyroid stimulating hormone concentrations. These thyroid hormone changes may be mediated in part by cytokines or other inflammatory mediators, acting at the level of the hypothalamus and pituitary, the thyroid gland, and the hepatic deiodinase system, as well as on binding of thyroxine to thyroid binding globulin. The degree of thyroid function disturbance correlates with disease severity and low levels of thyroid hormones predict a poor prognosis in several illnesses. It remains unresolved whether the hormone responses in the euthyroid sick syndrome represent part of an adaptive response, which lowers tissue energy requirements in the face of systemic illness, or a maladaptive response, which induces damaging tissue hypothyroidism. Consequently, the use of thyroid hormone therapy in the euthyroid sick syndrome is controversial. The small number of controlled trials performed to date have shown conflicting results on the cardiovascular effects of triiodothyronine, and none has had the statistical power to address the question of altered mortality. Future trials of therapy should concentrate on patients with severe nonthyroidal illness and a high mortality rate. Meanwhile, better understanding is needed of the impact of the altered thyroid hormone status on tissue function.
甲状腺激素浓度异常在多种非甲状腺疾病中很常见，会导致三碘甲状腺原氨酸、总甲状腺素和促甲状腺激素浓度降低。这些甲状腺激素变化可能部分由细胞因子或其他炎症介质介导，作用于下丘脑和垂体、甲状腺以及肝脏脱碘酶系统，也作用于甲状腺素与甲状腺结合球蛋白的结合。甲状腺功能紊乱的程度与疾病严重程度相关，甲状腺激素水平低预示着几种疾病的预后不良。甲状腺功能正常的病态综合征中的激素反应是代表适应性反应的一部分（面对全身性疾病时降低组织能量需求）还是代表适应不良反应（导致组织甲状腺功能减退）仍未解决。因此，甲状腺功能正常的病态综合征中甲状腺激素治疗的应用存在争议。迄今为止进行的少数对照试验对三碘甲状腺原氨酸的心血管效应显示出相互矛盾的结果，而且没有一项试验有足够的统计效力来解决死亡率改变的问题。未来的治疗试验应集中于患有严重非甲状腺疾病且死亡率高的患者。与此同时，需要更好地了解甲状腺激素状态改变对组织功能的影响。
