Thyroid function in children and adolescents with Hashimoto's thyroiditis after l-thyroxine discontinuation.

OBJECTIVE: Thyroid function may recover in patients with Hashimoto's thyroiditis (HT). DESIGN: To investigate thyroid function and the need to resume l-thyroxine treatment after its discontinuation. SETTING: Nine Italian pediatric endocrinology centers. PATIENTS: 148 children and adolescents (25 m and 123 f) with HT on treatment with l-thyroxine for at least one year. INTERVENTION AND MAIN OUTCOME MEASURE: Treatment was discontinued in all patients, and serum TSH and fT4 concentrations were measured at the time of treatment discontinuation and then after 2, 6, 12 and 24 months. Therapy with l-thyroxine was re-instituted when TSH rose >10 U/L and/or fT4 was below the normal range. The patients were followed up when TSH concentrations were between 5 and 10 U/L and fT4 was in the normal range. RESULTS: At baseline, TSH was in the normal range in 139 patients, and was between 5 and 10 U/L in 9 patients. Treatment was re-instituted after 2 months in 37 (25.5%) patients, after 6 months in 13 patients (6.99%), after 12 months in 12 patients (8.6%), and after 24 months in an additional 3 patients (3.1%). At 24 months, 34 patients (34.3%) still required no treatment. TSH concentration >10 U/L at the time of diagnosis was the only predictive factor for the deterioration of thyroid function after l-thyroxine discontinuation. CONCLUSIONS: This study confirms that not all children with HT need life-long therapy with l-thyroxine, and the discontinuation of treatment in patients with a TSH level <10 U/L at the time of diagnosis should be considered.