OBJECTIVETo compare differences in the intelligence and physical developmental levels of children with congenital hypothyroidism (CH) who received initial treatment at different times.

METHODSForty-nine children with CH diagnosed by neonatal screening between September 2008 and September 2011 were enrolled in this study. According to the timing of initial treatment with thyroid hormone, they were classified into two groups: <1 month and 1 to 3 months of life. At 6 months old, 1 year and 2 years old, their intelligence levels were evaluated by Gessell test. Their physical developmental levels were also measured. Their thyroid functions were examined with fluorescence immunoassay.

RESULTSWith treatment, there were no significant differences in thyroid hormones (FT3, FT4 and TSH) between the two groups (P>0.05) at 6 months old, 1 year and 2 years old. However, heights and weights in the <1 month treatment group were significantly higher than in the 1 to 3 months treatment group at all time points (P<0.05). At 6 months old, intelligence developmental levels in the <1 month treatment group were better than the 1 to 3 months treatment group (P<0.05) but significant differences were not noted at 1 and 2 years old (P>0.05).

CONCLUSIONSThe timing of initial treatment with thyroid hormone appears to be associated with the intelligence and physical development in children with CH. Treatment starting at less than 1 month of life contributes to improved physical and intelligence development compared with treatment starting at 1 to 3 months of life.