Graves' disease (GD) is extremely rare in children younger than 4 years of
age, but if not recognized and treated it can seriously interfere with grow
th and development. We report three unrelated children, all females, in who
m GD occurred before the age of 3. These children presented with goiter, ex
ophthalmos, tachycardia, and hyperactivity. Moreover, one showed a severe p
sychomotor delay, and had previously undergone surgery due to craniosynosto
sis; the other two manifested a language delay. All had high thyroid hormon
es and thyrotropin receptor antibody (TRAb) serum levels that clearly indic
ated autoimmune hyperthyroidism. In all of them, the disease presumably had
developed during the first or second year of life. No maternal history of
GD was present in two. The third child was born to a mother affected with G
D during pregnancy, but it is likely that her GD began to develop after 6 m
onths of life. These children are being treated with methimazole, and treat
ment is still necessary after 32 months. TRAb levels were persistently high
at follow-up. Psychological evaluation including language development at f
ollow-up was appropriate for age in two children; the third child improved,
but severe mental retardation is still evident. GD assessment in early chi
ldhood also needs to focus on psychological evaluation. Pediatricians shoul
d be aware of the possibility of permanent brain damage and craniosynostosi
s due to hyperthyroidism in infancy.