The clinical course of Hashimoto's thryoiditis in children and adolescents: 6 years longitudinal follow-up.

Forty-six children and adolescents with Hashimoto's thyroiditis were followed up for 5.9 +/- 0.3 years. The mean age at diagnosis was 12.4 +/- 1.7 years (range 9-15.4 yr). The patients were divided into three groups according to thyroid function: group 1 (n = 28) included patients who had normal concentrations of free thyroxine (FT4) and thyrotropin (TSH); group 2 (n = 8) included patients who had normal FT4 and elevated TSH, consistent with compensated hypothyroidism; group 3 (n = 10) included patients who had low FT4 and elevated TSH consistent with overt hypothyroidism. After 5.9 years of follow-up, four out of eight patients with compensated hypothyroidism had normal thyroid function and the other four patients developed overt hypothyroidism. Thyroxine therapy was administered in patients with overt hypothyroidism including the four patients with compensated hypothyroidism who later presented with overt hypothyroidism. All patients in both euthyroid and hypothyroid groups had normal growth and puberty. Final adult height was 0.43 +/- 0.80 SDS which was 1.58 +/- 3.03 cm above mid-parental height. The mean age at menarche (n = 43) was 12.4 +/- 1.1 years, which was not different from normal children. The goiter remained the same size in most of the patients with euthyroidism without thyroxine therapy, but decreased in patients with overt hypothyroidism after thyroxine therapy.