The natural history of the normal/mild elevated TSH serum levels in children and adolescents with Hashimoto's thyroiditis and isolated hyperthyrotropinaemia: a three year follow-up

Objective:  The natural history of Hashimoto's thyroiditis (HT), and of isolated hyperthyrotropinaemia (IH) is not well defined. We therefore studied the natural course of patients with HT and IH and looked for possible prognostic factors. Design:  Retrospective cross-sectional study Patients:  323 patients with HT (88 m and 235 f,), and 59 with IH (30 m, 29 f), mean age 9.9 ± 3.8 yrs were included in the study. When first examined, 236 of the children with HT had a normal TSH (G0) and in 87, it was elevated but <100% of the upper limit (G1). All IH subjects had elevated TSH. Potential risk factors for thyroid failure were evaluated after three years and included the presence or familiarity for endocrine/autoimmune diseases, premature birth, signs and symptoms of hypothyroidism, TSH levels, anti-thyroid antibodies and thyroid volume. Results HT:  Of those with HT, 170 G0 patients remained stable, 31 moved to G1, and 35 to G2 (hypothyroidism). 36 G1 children moved to G0, 17 remained stable and 34 moved to G2. Of patients with IH: 23 normalized, 28 remained stable, and 8 became overtly hypothyroid. In HT patients, the presence of coeliac disease, elevated TSH and TPOAb increased the risk of developing hypothyroidism by 4.0-, 3.4- and 3.5-fold, respectively. The increase of TSH levels during follow-up was strongly predictive of the development of hypothyroidism. In patients with IH, no predictive factor could be identified. Conclusions:  Coeliac disease, elevated TSH and TPOAb at presentation and a progressive increase of TSH are predictive factors for thyroid failure in HT patients.