Remission of Hashimoto's thyroiditis in a twelve-year-old girl with thyroid changes documented by ultrasonography.

Background: Although it is known that Hashimoto's thyroiditis in children and adolescents can go into long-term remission, and that treatment with thyroxine (T4) may not be necessary, it is difficult to quantify changes in the degree of autoimmune destruction of the thyroid. Here we report a patient in whom there was a relationship between functional and anatomical changes as assessed by hormone measurements and ultrasonography.

Summary: The patient was a 12-year-old girl with Hashimoto's thyroiditis who was initially euthyroid and later treated with 50 µg levo-T4 when her free T4 (fT4) had declined from 17 to 7 pmol/L (normal range, 8-22 pmol/L). At this time her thyroid-stimulating hormone (TSH) was 4.1 mIU/L (normal range, 0.30-4.0 mIU/L) and thyroid ultrasonography demonstrated features of early inflammation. Two years later, while on the same dose of T4, ultrasound examination revealed severe end-stage Hashimoto's thyroiditis and thyroid function tests showed a T4 of 14.0 pmol/L and TSH of 0.81 mIU/L. Twelve months later, however, the thyroid ultrasound had returned to almost normal with only minimal features of inflammation. Thyroid function tests showed a fT4 of 12.8 pmol/L and TSH of 0.75 mIU/L. Her T4 treatment was then stopped. Eight, 17, and 30 weeks after this, her fT4 was 16.8, 9.7, and 13.9 pmol/L, respectively, and her respective TSH values at the same times were 0.10, 2.24, and 0.75 mIU/L.

Conclusions: This is the first recording of serial thyroid ultrasound changes in a patient with Hashimoto's thyroiditis that paralleled changes in thyroid function. This indicates that thyroiditis can go into remission in some children. Thyroid ultrasound may be useful to make presumptive therapeutic decisions in children and adolescents with Hashimoto's thyroiditis whose dose of thyroid hormone seems to be less than is full replacement. Thyroid function tests, however, should ultimately guide T4 dosage.