Charkes N D
Section of Nuclear Medicine, Temple University Hospital, Philadelphia, Pennsylvania 19140, USA.
Thyroid. 1996 Oct;6(5):391-6. doi: 10.1089/thy.1996.6.391.
Subclinical hyperthyroidism, defined as serum thyroid hormone levels in the reference range with low serum TSH concentration, is a well recognized clinical entity, but little information is available concerning the prevalence of the disorders that produce it. We conducted a 24-month retrospective survey of subclinical hyperthyroidism patients referred to a university hospital nuclear medicine service for diagnostic studies. Twenty-four consecutive patients were evaluated (22 outpatients and 2 inpatients). All patients had highly sensitive TSH determination, thyroid hormone levels, radioiodine uptake and scan (except for 2 postpartum women), and, selectively, TSH-receptor antibody (TRAb), serum thyroglobulin, antithyroid antibodies, T3-suppression test, and erythrocyte sedimentation rate. A TSH value of about 0.1 microIU/mL was used as the cutoff. Only one patient in the group had a nonthyroidal disorder. In 14 patients (61%) subclinical hyperthyroidism was self-limited, due to silent thyroiditis (5 patients), iodine-induced hyperthyroidism (3 patients), postpartum thyroiditis (2 patients), subacute thyroiditis (2 patients), and probable hemorrhage into a functioning nodule (2 patients). Of the non-self-limited disorders (39%), Graves' disease accounted for 6 patients and solitary or multinodular goiter for 3. Graves' disease proved difficult to diagnose because the thyroid gland was normal in size in two of the six patients, TRAb was positive in only two of six, and the radioiodine uptake and gradient were normal in all six; the T3-suppression test was positive in two of two patients. We conclude that the causes of subclinical hyperthyroidism are the disorders that commonly produce overt thyrotoxicosis in medical practice, Graves' disease being the most frequent. However, the tests used to diagnose overt Graves' disease often fail in the setting of subclinical hyperthyroidism, except possibly the T3-suppression test.
亚临床甲状腺功能亢进症的定义为血清甲状腺激素水平在参考范围内但血清促甲状腺激素（TSH）浓度较低，它是一种已被充分认识的临床病症，但关于导致该病症的疾病患病率的信息却很少。我们对转诊至大学医院核医学科进行诊断检查的亚临床甲状腺功能亢进症患者进行了为期24个月的回顾性调查。连续评估了24例患者（22例门诊患者和2例住院患者）。所有患者均进行了高敏TSH测定、甲状腺激素水平检测、放射性碘摄取和扫描（2例产后妇女除外），并选择性地检测了促甲状腺激素受体抗体（TRAb）、血清甲状腺球蛋白、抗甲状腺抗体、T3抑制试验和红细胞沉降率。TSH值约0.1微国际单位/毫升被用作临界值。该组中只有1例患者患有非甲状腺疾病。14例患者（61%）的亚临床甲状腺功能亢进症为自限性，病因包括寂静性甲状腺炎（5例）、碘致甲状腺功能亢进症（3例）、产后甲状腺炎（2例）、亚急性甲状腺炎（2例）以及可能是功能性结节内出血（2例）。在非自限性疾病中（39%），格雷夫斯病占6例，单结节或多结节性甲状腺肿占3例。格雷夫斯病难以诊断，因为6例患者中有2例甲状腺大小正常，6例中只有2例TRAb呈阳性，且6例患者的放射性碘摄取和梯度均正常；2例患者中2例T3抑制试验呈阳性。我们得出结论，亚临床甲状腺功能亢进症的病因是在医疗实践中通常导致显性甲状腺毒症的疾病，格雷夫斯病最为常见。然而，用于诊断显性格雷夫斯病的检测方法在亚临床甲状腺功能亢进症的情况下往往失效，可能T3抑制试验除外。
