Appropriate methimazole dosing for initial treatment of childhood Graves' 
disease is uncertain. A retrospective chart review was performed on 5 to 17 
year-old children treated for Graves' disease. Patients were divided into two 
groups depending on initial methimazole dosing: low-dose and high-dose regimens 
using <0.5 mg/kg/day and >0.5 mg/kg/day, respectively. The low-dose regimen was 
effective in 5/12 (42%) of patients and the high-dose regimen was effective in 
27/33 (82%) of patients (p = 0.016). There was also a statistically significant 
dose/time interaction for levels of free thyroxine (T4) (p = 0.025). During 
treatment, 63.3% of diagnosable samples showed unambiguous hyperthyroidism or 
triiodothyronine (T3) toxicosis, 16.7% elevated free T3 with normal free T4 and 
T3 levels, indicating borderline hyperthyroidism, and 20% showed 
thyroid-stimulating hormone (TSH) suppression with normal or low levels of free 
T4 and free T3, indicating delayed recovery of pituitary TSH secretion. Free T3 
levels combined with concurrent TSH levels permit differentiation of mild 
hyperthyroidism from delayed pituitary recovery.