School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
Clin Endocrinol (Oxf). 2013 Jan;78(1):1-8. doi: 10.1111/cen.12011.
Mild thyroid dysfunction is common, and more prevalent than overt hyper- and hypothyroidism. Subclinical (mild) thyroid dysfunction is a biochemical entity characterized by an abnormality of serum TSH associated with normal serum thyroid hormone concentrations. Subclinical hyperthyroidism is thus defined as low or suppressed serum TSH with normal serum-free T4 and T3, while subclinical hypothyroidism is defined as raised serum TSH with normal circulating T4. These biochemical abnormalities are part of the much wider spectrum of thyroid dysfunction which includes overt hyperthyroidism and overt hypothyroidism, but by no means always indicate underlying thyroid disease. There is much debate about the significance of mild abnormalities of thyroid function in terms of symptoms and potential associations with long-term morbidity and mortality and hence much debate about whether to screen for these abnormalities, and, once identified, whether to treat or monitor, and if so, how? Our knowledge base has increased significantly in recent years, principally because studies of large cohorts have begun to define the epidemiology and associations of mild thyroid dysfunction (including short-term and long-term outcomes) and a small but increasing number of randomized-controlled intervention studies have been reported. There is, however, much to learn about these disorders and, given their prevalence, their impact on health.
轻度甲状腺功能障碍很常见，比明显的甲状腺功能亢进和甲状腺功能减退更为普遍。亚临床（轻度）甲状腺功能障碍是一种以血清 TSH 异常伴正常血清甲状腺激素浓度为特征的生化实体。因此，亚临床甲状腺功能亢进定义为血清 TSH 降低或抑制，而游离 T4 和 T3 正常，而亚临床甲状腺功能减退则定义为血清 TSH 升高，而循环 T4 正常。这些生化异常是甲状腺功能障碍更为广泛谱的一部分，包括明显的甲状腺功能亢进和明显的甲状腺功能减退，但并非总是表明存在甲状腺疾病。对于轻度甲状腺功能异常在症状方面的意义以及与长期发病率和死亡率的潜在关联存在很多争议，因此对于是否要筛查这些异常存在很多争议，一旦发现，是否要治疗或监测，如果是，如何治疗？近年来，我们的知识库有了显著的增长，主要是因为对大型队列的研究开始定义轻度甲状腺功能障碍的流行病学和关联（包括短期和长期结果），并且已经报告了一些数量虽小但不断增加的随机对照干预研究。然而，对于这些疾病还有很多需要了解，考虑到它们的普遍性，它们对健康的影响。
