The Prevalence of Antithyroid Autoantibodies in Normal Korean Population(*): Age, Sex Distribution and Its Relation to Thyroid Function

The prevalence of antithyroid autoantibodies and the relationship between the presence of autoantibodies and thyroid functions were studied in 848 apparently normal Korean adults with tanned red cell agglutination technique. Results are summarized as follows: 1) The prevalence of antimicrosimal antibody (MCHA) and antithyroglobulin antibody (TGHA) were 4.4% and 1.9% in 458 males, and 12.4% and 5.0% in 390 females, respectively. Both autoantibodies were more prevalent in female (p<0.001, p<0.01). 2) The age-specific prevalence of MCHA was 4.0% in their twenties, 10.1% in their thirties, 12.5% in their forties, 12.0% in their fifties, 8.3% over sixty, and those of TGHA were 2.0% in their twenties, 3.0% in their thirties, 7.0% in their forties, 4.2% in their fifties, 2.5% in subjects over sixty, respectively. Both showed maximal values around forty and fifty and tended to be lower thereafter. 3) Mean T(3), T(4) and TSH values of high titer group (⩾1:100(2)) (n=32) were 125 ± 20.6 ng/dl, 9.1 ± 1.7μg/dl and 4.0 ± 1.8 uU/ml, and those of low titer group (<1:100(2)) (n=44) were 134 ± 24.3 ng/dl, 9.6 ± 1.7 ug/dl and 3.2 ± 1.2 νU/ml. T(3) was lower and TSH, higher in high titer group than in low titer group (p<0.05, p<0.05), and no significant difference was observed in T(4) level (p<0.1). In conclusion, the prevalence of MCHA and TGHA were higher in apparently normal females than in males with their peaks around forty and fifty, being lower thereafter, and antithyroid autoantibody of high titer (⩾1:100(2)) was related to alteration of thyroid functions suggesting the existence of “subclinical autoimmune thyroiditis” state.