Neurodevelopmental outcome of children with congenital hypothyroidism: relationship with the time of initiation of treatment

Background: Congenital hypothyroidism (CH) is one of the leading causes of preventable mental retardation in children. Normal neurological development can be achieved by early and effective treatment. The aim of the study was to assess neuro-developmental status of children with congenital hypothyroidism who were on treatment with oral levothyroxine and compare neurodevelopmental outcome in relation to time of initiation of treatment.
Methodology: This was a prospective observational study conducted in the Pediatric Endocrine Outpatient Department (OPD), BSMMU from March 2016 to February 2018. Fifty children aged 1 month to 48 months with congenital hypothyroidism who treated with levothyroxine during the study period were included in this study. Patients were divided into 4 groups on the basis of age at diagnosis and starting of treatment: Group I (started by one month of age), Group II (>1 months - 3 months of age), Group III (> 3 months - 12 months of age), Group IV (>12 months of age). Neurodevelopmental status in four domains such as gross motor, fine motor, cognition and language were assessed by Bayley Scales of Infant and Toddler Development (BSID III) during 3 months and 6 months follow up visit. Hearing screening was also performed during 3 months follow up visit.
Results: There were 12 patients in group I, 14 in group II, 14 in group III and 10 patients in group IV. Statistical significant differences in cognition and language were found during 3 months (p value < 0.05) and 6 months (p value < 0.01) follow up visit among four groups. Cognitive function was impaired 41% patients in group I, 50% in group II, 92.9% in group III and 90% in group IV and delayed language was observed 16.7% in group I, 50% in group II , 78.6% in group III and 70% in group IV during 3 months follow up visit. During 6 months follow up visit 25% patients in group I, 57.1% in group II, 92.9% in group III, 90 % in group IV had delay in cognitive function. However, 8.3% patients in group I, 28.6% in group II, 71.4% in group III and 60% in group IV had delay in language. Regarding hearing screening, gross motor and fine motor functions there were no significant differences among four groups of patients.
Conclusion: Patients who were started treatment early had favorable outcome in cognitive and language domains of development in comparison to patients with congenital hypothyroidism who had delay in starting treatment.