Higher serum thyroid autoantibody value is a risk factor of hypothyroidism in children and young adults with chronic thyroiditis.

Thyroid function in patients with chronic thyroiditis (CT) varies depending on the clinical course. Serum antithyroglobulin antibody (TgAb) and antithyroid peroxidase antibody (TPOAb) levels may be used to predict hypothyroidism in CT. In this retrospective cohort study, patients with CT, defined as having a high TgAb or TPOAb value, were divided into a hypothyroid group (HG) and euthyroid group (EG), after a mean follow-up of 2.5 years. The definitions of the two groups was based on the maximum TSH value from the initial measurement to the most recent follow-up: HG was defined as TSH 10.0 μIU/mL or higher, and EG was defined as TSH < 10.0 μIU/mL. There were 20 and 113 patients in the HG and EG, respectively. There were no significant differences in age, sex, underlying diseases, or TgAb and TPOAb levels between the groups. Receiver operating characteristic curve analyses of TgAb and TPOAb values for predicting thyroid function showed areas under the curve of 0.714 and 0.757, respectively. The value with the highest diagnostic accuracy was 106 IU/mL for TgAb and 16 IU/mL for TPOAb. Thus, TgAb > 106 IU/mL and TPOAb > 16 IU/mL may predict hypothyroidism in children and young adults with CT.