Prevalence of Subclinical Hypothyroidism in Two Population Based-cohort: Ansung and KLoSHA Cohort in Korea

Abstract

Background and Objectives :We examined the prevalence of subclinical hypothyroidism (SCH) in Korean population.

Materials and Methods : Using data from two cohorts, Ansung cohort consist of adults between 40 and 70 years old and Korean Longitudinal Study on Health and Aging (KLoSHA) study consist of elderly subjects over 65 years old, we examined the prevalence of SCH and the association of age with SCH, free T4 and thyrotropin (TSH).

Results:The prevalence of SCH was 11.7% in Ansung cohort and 17.3% in KoSHA study. The prevalence of SCH increased with advanced age in Ansung cohort, especially in the male subjects. In the male subjects of Ansung cohort, serum free T4 decreased and TSH increased with advanced age, whereas age was not associated with free T4 and TSH concentration in the female subjects. In KLoSHA study, age did not show significant association with prevalence of SCH and concentrations of free T4 and TSH. Anti- thyroidperoxidase (TPO) antibody was associated with SCH, however, it did not show significant association with advanced age in both cohorts.

Conclusion: In Korean population, the prevalence of SCH was 11.7% in adults and 17.3% in elderly subjects. The prevalence of SCH increased with advanced age, however, it did not increase any more in elderly subjects.