Amouzegar Atieh, Ghaemmaghami Zahra, Beigy Maani, Gharibzadeh Safoora, Mehran Ladan, Tohidi Maryam, Azizi Fereidoun
1 Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences , Tehran, Iran .
2 Students Scientific Research Center, Tehran University of Medical Sciences , Tehran, Iran .
Thyroid. 2017 May;27(5):616-625. doi: 10.1089/thy.2016.0409. Epub 2017 Mar 16.
Considering the limited data available on the natural course of euthyroidism, this study was designed to evaluate the progression in time from euthyroidism to subclinical or overt hypo- or hyperthyroidism.
This study was conducted within the framework of the Tehran Thyroid Cohort Study, in which 5783 individuals aged 40.4 ± 0.2 years were followed for six years. The overall loss to follow-up rate was 8.3%. After applying exclusion criteria, data of 4204 euthyroid subjects remained for analysis of a six-year natural course analysis. Thyroid function tests, clinical characteristics, and metabolic characteristics were assessed at baseline and every three years.
The annual incidence rates [confidence intervals (CI)] of subclinical and overt hypothyroidism were 7.62 [CI 7.39-7.85) and 2.0 [CI 1.94-2.06] per 1000 persons, respectively. For thyroid hyperfunction, the annual incidence rates of subclinical and overt hyperthyroidism were 0.92 [0.90-0.95) and 0.68 [0.66-0.70) per 1000 persons, respectively. Euthyroid persistency was 93.24% during 6 years. Predictive factors for conversion to thyroid dysfunction were thyrotropin, free thyroxine and thyroid peroxidase antibody levels, sex, and smoking. Criteria for early diagnosis of hypothyroidism (i.e., sensitivity of 94% and specificity of 82%, p < 0.0001) were obtained based on baseline and three-year follow-ups of thyroid function tests and thyroid peroxidase antibody. Early diagnosis of hypothyroidism was significantly associated with impaired glucose tolerance (relative risk with 3.03 [CI 1.36-6.75]; p = 0.007), high cholesterol (relative risk 2.46 [CI 1.45-4.18]; p = 0.001), obesity (relative risk 2.92 [CI 1.64-5.2]; p < 0.001), and hypertension (relative risk 1.68 [CI 1.53-1.84]; p < 0.04).
This study shows that after a six-year follow-up in an iodine sufficient area, 6.7% of euthyroid subjects were found to progress to thyroid dysfunction, in particular subclinical hypothyroidism.
鉴于关于甲状腺功能正常自然病程的可用数据有限，本研究旨在评估从甲状腺功能正常进展至亚临床或显性甲状腺功能减退或亢进的时间进程。
本研究在德黑兰甲状腺队列研究框架内进行，对5783名年龄为40.4±0.2岁的个体进行了为期六年的随访。总体随访失访率为8.3%。应用排除标准后，4204名甲状腺功能正常受试者的数据留作六年自然病程分析。在基线时以及每三年评估一次甲状腺功能测试、临床特征和代谢特征。
亚临床和显性甲状腺功能减退的年发病率[置信区间（CI）]分别为每1000人7.62[CI 7.39 - 7.85]和2.0[CI 1.94 - 2.06]。对于甲状腺功能亢进，亚临床和显性甲状腺功能亢进的年发病率分别为每1000人0.92[0.90 - 0.95]和0.68[0.66 - 0.70]。六年期间甲状腺功能正常的持续率为93.24%。甲状腺功能转换为甲状腺功能障碍的预测因素为促甲状腺激素、游离甲状腺素和甲状腺过氧化物酶抗体水平、性别和吸烟。基于甲状腺功能测试和甲状腺过氧化物酶抗体的基线及三年随访结果，得出甲状腺功能减退的早期诊断标准（即敏感性为94%，特异性为82%，p < 0.0001）。甲状腺功能减退的早期诊断与糖耐量受损（相对风险为3.03[CI 1.36 - 6.75]；p = 0.007）、高胆固醇（相对风险2.46[CI 1.45 - 4.18]；p = 0.001）、肥胖（相对风险2.92[CI 1.64 - 5.2]；p < 0.001）和高血压（相对风险1.68[CI 1.53 - 1.84]；p < 0.04）显著相关。
本研究表明，在碘充足地区进行六年随访后，发现6.7%的甲状腺功能正常受试者进展为甲状腺功能障碍，尤其是亚临床甲状腺功能减退。
