ROLE OF THYROID AUTOANTIBODIES IN PREDICTING PROGRESSION OF SUBCLINICAL HYPOTHYROIDISM: A PROSPECTIVE COHORT STUDY

Abstract

Background:
Subclinical hypothyroidism (SCH) is a common thyroid disorder characterized by elevated serum thyroid-stimulating hormone (TSH) levels with normal free thyroxine (FT4) concentrations. Although many patients remain stable, a proportion progress to overt hypothyroidism. Identification of reliable predictors of progression is essential for appropriate monitoring and management. Thyroid autoantibodies, particularly thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), may serve as important markers of autoimmune thyroid dysfunction and disease progression.

Objectives:
To evaluate the role of thyroid autoantibodies in predicting progression of subclinical hypothyroidism to overt hypothyroidism and to identify clinical and biochemical factors associated with disease progression.

Methods:
A prospective cohort study was conducted among patients diagnosed with subclinical hypothyroidism. Baseline clinical characteristics, serum TSH, FT4, TPOAb, and TgAb levels were assessed at enrollment. Patients were followed prospectively, and progression to overt hypothyroidism was defined by elevated TSH levels with reduced FT4 concentrations during follow-up. The association between thyroid autoantibody status and progression was analyzed using appropriate statistical methods.

Results:
Among the enrolled patients, a proportion progressed to overt hypothyroidism during follow-up. Progression was significantly higher among individuals with positive thyroid autoantibodies, particularly TPOAb positivity. Patients who progressed had higher baseline TSH levels and lower FT4 concentrations compared with those who remained stable. Multivariate analysis demonstrated that TPOAb positivity and higher baseline TSH levels were independent predictors of progression.

Conclusion:
Thyroid autoantibody positivity, especially TPOAb, is an important predictor of progression from subclinical hypothyroidism to overt hypothyroidism. Assessment of thyroid autoantibodies along with baseline thyroid function tests may help identify high-risk patients and guide individualized follow-up and management strategies.