Natural History of Mild Subclinical Hypothyroidism in a Middle-Aged and Elderly Chinese Population: A Prospective Study

Presentation Number: OR38-2
Date of Presentation: April 3rd, 2017

Xiang Li*1, Donghu Zhen2, Meng Zhao1, Lu Liu1, Qingbo Guan1, Haiqing Zhang1, Xulei Tang3 and Ling Gao1
1Shandong Provincial Hospital affiliated to Shandong University, Jinan, China, 2The First Hospital of Lanzhou University, 3The First Hospital of Lanzhou University, Lanzhou, China

Abstract

Background: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. However, the answers remain quite unclear. We aimed to clarify the natural history of mild subclinical hypothyroidism and prognostic factors related to it.

Methods: This is a prospective population-based study. We measured thyroid function in 11000 participants in the REACTION study and followed up 505 newly diagnosed mild SCH patients aged 40-years or older between 2011 and 2014, and measured thyroid function again in 2014. Logistic regression analysis was used to seek baseline parameters associated with the natural outcomes of mild SCH.

Results: 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 5.20-6.20 mmol/L or >6.20 mmol/L vs. <5.20mmol/L, p = .048 and .006, respectively) or positive thyroid peroxidase antibodies (TPOAb, p = .009) had higher risks of progression to OH, while those with higher baseline creatinine (CR, between 62.31-70.80 mmol/L or >70.80 mmol/L vs. ≤57.10 mmol/L, p = .031 and .004, respectively), higher baseline thyrotropin (≥7 mIU/L, p < .001) or older (>60 years vs. ≤50 years, p = .012) had lower odds of reverting to euthyroidism.

Conclusions: Our present study demonstrated that nearly half of mild SCH patients revert to euthyroidism. In mild SCH patients, TPOAb and TC seem to be more important predictors of progression to overt hypothyroidism than initial TSH, whereas high baseline thyrotropin or CR were negative correlated with reversion to euthyroidism. TC and CR might be valuable as prognostic factors in mild SCH. These patients might need more frequent monitoring of thyroid function. Future studies should exam the possible benefits of L-thyroxine treatment in patients with high TC or CR levels.

The laboratory reference range were as follows: FT4, 12-22 pmol/L (0.94-1.72 ng/dL); TSH, 0.27-4.2 mIU/L. Positivity for TPOAb was considered when the serum concentration of this antibody was higher than 34 IU/mL.

 

Nothing to Disclose: XL, DZ, MZ, LL, QG, HZ, XT, LG