Clinical evolution of autoimmune thyroiditis in children and adolescents

Few studies have addressed the clinical evolution of autoimmune thyroiditis (AIT) occurring in childhood and scant data are available on the role of thyroid ultrasonography. We aimed to evaluate the natural history of AIT diagnosed in children and adolescents and to assess the possible prognostic role of ultrasonography.

Retrospective case series prospectively followed up for a further 3-year period.

A series of 23 patients with AIT, diagnosed before 18 years of age from 1994 to 2004, was further followed up from 2005 to 2007 with clinical, laboratory, and ultrasound evaluation. Hypothyroid patients were treated with levothyroxine (LT(4)), while euthyroid patients were left untreated. Patients with subclinical hypothyroidism were also evaluated 40 days after LT(4) withdrawal. At diagnosis seven patients were euthyroid, 14 with subclinical hypothyroidism, and two with overt hypothyroidism. Median follow-up was 4.7 years. At last follow-up visit, none of the seven euthyroid patients had developed hypothyroidism. Three of the 14 patients with subclinical hypothyroidism recovered a normal thyroid function while only one patient showed an increase in TSH level. By serological screening we identified three patients with other autoimmune disorders.

In young patients with normal or mildly increased TSH levels and minimal echographic changes, AIT may remain stationary for years. In fact, patients with subclinical hypothyroidism recover a normal thyroid function in approximately 20% of cases. In patients with subclinical hypothyroidism and goiter, LT(4) therapy may induce thyroid size reduction. Screening for other autoimmune disorders is useful to identify patients that need further diagnostic assessment.