Natural history of mild subclinical hypothyroidism in a middle-aged and elderly Chinese population: a prospective study

• Published in: ENDOCRINE JOURNAL Vol. 64; no. 4; pp. 437 - 447
• Main Authors: Li, Xiang, Zhen, Donghu, Zhao, Meng, Liu, Lu, Guan, Qingbo, Zhang, Haiqing, Ge, Shujian, Tang, Xulei, Gao, Ling
• Format: Journal Article
• Language: English; Japanese
• Published: Japan The Japan Endocrine Society 2017; Japan Science and Technology Agency
• Subjects: Adult; Age Factors; Aged; Aged, 80 and over; Aging - ethnology; Aging - physiology; Asian Continental Ancestry Group - statistics & numerical data; Asymptomatic Diseases; China - epidemiology; Cholesterol; Creatinine; Disease Progression; Female; Geriatrics; Health risk assessment; Humans; Hypothyroidism; Hypothyroidism - epidemiology; Hypothyroidism - pathology; Iodide peroxidase; Male; Middle Aged; Natural history; Patients; Peroxidase; Population studies; Prevalence; Prospective study; Risk factors; Severity of Illness Index; Thyroid; Thyroid gland; Thyroid-stimulating hormone; Thyrotropin; Thyrotropin; Hypothyroidism; Prospective study; Natural history; Risk factors
• ISSN: 0918-8959; 1348-4540
• DOI: 10.1507/endocrj.EJ16-0549

Subclinical hypothyroidism (SCH) has a high global prevalence. Most SCH patients have mild cases (thyrotropin ≤10 mIU/L). Treatment recommendations for mild SCH are controversial, which raises concerns about the natural history of mild SCH. We aimed to clarify the natural history of mild SCH. This is a prospective population-based study. We measured thyroid function in 11,000 participants in the REACTION study and followed 505 newly diagnosed mild SCH patients aged 40-years or older between 2011 and 2014. Logistic regression analysis was used to seek baseline parameters associated with the natural outcomes of mild SCH. Among 505 mild SCH patients, 221 (43.8%) had persistent SCH, 251 (49.7%) reverted to euthyroidism, and 17 (3.4%) progressed to overt hypothyroidism (OH). Patients with higher baseline total cholesterol (TC, between 201.0-240.0 mg/dL or >240.0 mg/dL vs. <201.0 mg/dL, p = 0.048 and 0.006, respectively) or positive thyroid peroxidase antibodies (TPOAb, p = 0.009) had higher risks of progression to OH, while those with higher baseline creatinine (CR, between 0.71-0.80 mg/dL or >0.80 mg/dL vs. ≤0.65 mg/dL, p = 0.031 and 0.004, respectively), higher baseline thyrotropin (≥7 mIU/L, p < 0.001) or older (>60 years vs. ≤50 years, p = 0.012) had lower odds of reverting to euthyroidism. In conclusion, TPOAb and TC seem to be more important predictors of progression to OH than initial thyrotropin, whereas high baseline thyrotropin or CR were negative correlated with reversion to euthyroidism. The prognostic value of TC and CR in mild SCH should be considered.