Objectives: To describe the natural course of "subclinical" hypothyroidism due to autoimmune thyroiditis in children and adolescents, and to determine whether, like euthyroid childhood autoimmune thyroiditis, it would also run a more benign course in this age group than in adults.
Design: Case series.
Setting: Pediatric endocrine clinic in a tertiary medical center.
Patients: Eighteen patients (age range, 5 to 19 years) with juvenile autoimmune thyroiditis and an initially elevated serum thyrotropin (thyroid-stimulating hormone) concentration were followed up from documentation of the elevated serum thyrotropin concentration for a mean of 5.8 years. Eleven patients never received treatment, and seven were followed up after discontinuation of therapy.
Main outcome measures: Changes in the serum thyrotropin and thyroxine concentrations and thyroid gland size, as well as signs and symptoms of hypothyroidism, were monitored throughout the observation period.
Results: The mean duration of observation during which the patients did not receive any therapy was 47.3 months. At the end of the observation period, seven patients were euthyroid, 10 continued to have an elevated serum thyrotropin concentration with a normal serum thyroxine concentration, and one became hypothyroid.
Conclusions: "Subclinical" juvenile hypothyroidism may be a benign and remitting process in many older children and adolescents. In view of the undefined risks of levothyroxine sodium therapy, it may be possible to follow up expectantly selected younger patients with a minimally elevated serum thyrotropin concentration, rather than to treat them empirically.