Longitudinal population-based study of progression rates for borderline thyroid-stimulating hormone abnormalities

Area of Science:

• Endocrinology
• Clinical Biochemistry
• Population Health

Background:

• Thyroid-stimulating hormone (TSH) is the primary test for thyroid function.
• Borderline TSH results are common but their progression is not well understood.
• Current guidelines lack specific recommendations for managing borderline TSH levels.

Purpose of the Study:

• To investigate risk factors for progression of borderline TSH to overt thyroid dysfunction.
• To determine the likelihood of borderline TSH abnormalities becoming overt.
• To inform clinical management strategies for patients with borderline TSH.

Main Methods:

• Retrospective longitudinal study using population-based TSH test data (1996-2013).
• Kaplan-Meier methodology to analyze conversion time from borderline to overt TSH levels.
• Identified borderline elevated TSH (BeTSH) and suppressed TSH (BsTSH) groups.

Main Results:

• Over 1.29 million TSH tests analyzed from 367,917 patients.
• Patients aged ≥80 years had the highest risk of progressing from borderline elevated TSH (HR=2.09).
• Patients aged 60-79 years had the highest risk of progressing from borderline suppressed TSH (HR=2.47).

Conclusions:

• Patient age is a significant risk factor for TSH progression.
• Follow-up intervals for borderline TSH should consider age.
• Age-specific monitoring can improve management of thyroid function.