Jayme J J, Ladenson P W
Division of Endocrinology and Metabolism, Johns Hopkins University School of Medicine, Baltimore, MD 21287-4904, USA.
Trends Endocrinol Metab. 1994 Mar;5(2):79-86. doi: 10.1016/1043-2760(94)90006-x.
Subclinical thyroid dysfunction is more common in older persons. By definition, these disorders are recognized by isolated elevation or suppression of the serum TSH concentration, in association with a normal serum free thyroxine level. Among individuals over 65 years old, subclinical hypothyroidism is found in approximately 10% of women and approximately 3% of men. It is most commonly due to autoimmune thyroiditis or previous treatment for hyperthyroidism. There may be three indications for L-thyroxine therapy: (a) presence of antithyroid antibodies, indicating substantial risk of progression to over hypothyroidism; (b) symptoms consistent with thyroid hormone deficiency; and (c) an elevated serum LDL-cholesterol. Subclinical hyperthyroidism is present in approximately 1%-2% of older persons. The most common cause is excessive thyroid hormone therapy, followed by mild endogenous hyperthyroidism due to Graves' disease or nodular goiter. These can be differentiated from other causes of low serum TSH concentration based on clinical and other laboratory and radionuclide scan criteria. The most serious consequences of subclinical hyperthyroidism are atrial fibrillation and osteoporosis, to which elderly patients are particularly predisposed.
亚临床甲状腺功能障碍在老年人中更为常见。根据定义，这些疾病通过血清促甲状腺激素（TSH）浓度的单独升高或降低以及正常的血清游离甲状腺素水平来识别。在65岁以上的个体中，约10%的女性和约3%的男性存在亚临床甲状腺功能减退。其最常见的原因是自身免疫性甲状腺炎或既往的甲亢治疗。左甲状腺素治疗可能有三个指征：（a）存在抗甲状腺抗体，表明进展为明显甲状腺功能减退的风险很大；（b）与甲状腺激素缺乏一致的症状；（c）血清低密度脂蛋白胆固醇升高。约1%-2%的老年人存在亚临床甲亢。最常见的原因是甲状腺激素治疗过量，其次是由格雷夫斯病或结节性甲状腺肿引起的轻度内源性甲亢。根据临床、其他实验室及放射性核素扫描标准，这些情况可与血清TSH浓度降低的其他原因相鉴别。亚临床甲亢最严重的后果是心房颤动和骨质疏松，老年患者尤其易患。
