Department of Endocrinology, Shengjing Affiliated Hospital of China Medical University, Shenyang, P.R. China.
Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China.
Thyroid. 2018 Dec;28(12):1571-1579. doi: 10.1089/thy.2017.0715. Epub 2018 Nov 27.
The fact that serum thyrotropin (TSH) levels increase with age may influence the diagnosis of thyroid diseases in older adults. This study aimed to establish an age-specific serum TSH reference range, examine the prevalence of thyroid diseases in older adults ≥65 years, and analyze the risk factors. A cross-sectional study of adult populations in 10 cities in China was conducted from 2010 to 2011. A total of 15,008 subjects were randomly selected and completed the present study. Urinary iodine concentration, serum TSH, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) titers were measured. Thyroid ultrasonography and questionnaires were completed by all the subjects. When the TSH level was abnormal, free thyroxine and/or free triiodothyronine levels were measured. When the reference range of the general population was used, the prevalence rates of overt hypothyroidism (Ohypo) and subclinical hypothyroidism (Shypo) in older adults ≥65 years were significantly higher than those in younger adults <65 years (2.09% vs. 0.80% and 19.87% vs. 16.23%, respectively; < 0.001). Positive TPOAb and positive TgAb were associated with the prevalence of Shypo in older adults. An age-specific serum TSH reference range was formulated according to guidelines set forth by the National Academy of Clinical Biochemistry. Both the median and upper limit values of serum TSH in older adults were higher than those in younger adults (2.58 [0.75-8.86] mIU/L vs. 2.38 [0.76-6.57] mIU/L; < 0.001). Using the age-specific serum TSH reference range, the prevalence of Shypo in older adults was 3.3%, which was significantly lower than the prevalence based on the reference range of the general population (3.3% vs. 19.87%). The prevalence rates of Ohypo, overt hyperthyroidism (Ohyper), and subclinical hyperthyroidism (Shyper) did not change much (Ohypo: 1.6% vs. 2.09%; Ohyper: 0.7% vs. 0.52%; and Shyper: 3.8% vs. 0.73%). Positive TPOAb, but not positive TgAb, was also associated with the prevalence of Shypo as diagnosed with the age-specific serum TSH reference range. The serum TSH level increases with age, which may represent a normal compensatory phenomenon in older adults ≥65 years. To prevent misdiagnosis and mistreatment, the use of an age-specific serum TSH reference range is recommended in older adults for the diagnosis of thyroid diseases.
血清促甲状腺激素（TSH）水平随年龄增长而升高这一事实可能会影响老年人甲状腺疾病的诊断。本研究旨在建立年龄特异性血清 TSH 参考范围，检查≥65 岁老年人中甲状腺疾病的患病率，并分析其危险因素。本研究为 2010 年至 2011 年期间在中国 10 个城市进行的一项成人人群的横断面研究。共随机选择了 15008 名受试者并完成了本研究。测量了尿碘浓度、血清 TSH、甲状腺过氧化物酶抗体（TPOAb）和甲状腺球蛋白抗体（TgAb）滴度。所有受试者均完成了甲状腺超声检查和问卷调查。当 TSH 水平异常时，测量游离甲状腺素和/或游离三碘甲状腺原氨酸水平。当使用一般人群的参考范围时，≥65 岁的老年人中显性甲状腺功能减退症（Ohypo）和亚临床甲状腺功能减退症（Shypo）的患病率明显高于<65 岁的年轻人（2.09%比 0.80%和 19.87%比 16.23%；<0.001）。阳性 TPOAb 和阳性 TgAb 与老年人 Shypo 的患病率相关。根据临床生物化学国家科学院制定的指南制定了年龄特异性血清 TSH 参考范围。老年人的血清 TSH 中位数和上限值均高于年轻人（2.58 [0.75-8.86] mIU/L 比 2.38 [0.76-6.57] mIU/L；<0.001）。使用年龄特异性血清 TSH 参考范围，老年人 Shypo 的患病率为 3.3%，明显低于基于一般人群参考范围的患病率（3.3%比 19.87%）。Ohypo、显性甲状腺功能亢进症（Ohyper）和亚临床甲状腺功能亢进症（Shyper）的患病率变化不大（Ohypo：1.6%比 2.09%；Ohyper：0.7%比 0.52%；Shyper：3.8%比 0.73%）。阳性 TPOAb，而不是阳性 TgAb，也与年龄特异性血清 TSH 参考范围诊断的 Shypo 患病率相关。血清 TSH 水平随年龄增长而升高，这可能代表≥65 岁老年人的正常代偿现象。为避免误诊和误治，建议≥65 岁老年人使用年龄特异性血清 TSH 参考范围诊断甲状腺疾病。
