Neurocognitive skills in children with congenital hypothyroidism attending the endocrine clinic of the Professorial Unit of the Lady Ridgeway Hospital for Children, Colombo

Abstract

Background: Early thyroxine replacement prevents intellectual impairment due to congenital hypothyroidism (CHT). There is minimal evidence on neurodevelopmental outcome of children commenced on thyroxine during early infancy from countries not screening for CHT. Objective: To assess the neurocognitive skills of children with CHT of age group 6-10 years, attending the endocrine clinic of the Professorial Paediatric Unit, LRH compared to age matched controls and to assess the influence of age at diagnosis, initial thyroid stimulating hormone (TSH) levels, thyroxine commencement dose and number of clinic visits in the first year on neurocognitive skills. Method: A retrospective study was carried out from 1st January 2010 to 1st January 2011 on children with CHT of age group 6-10 years, followed up in the endocrine clinic of the Professorial Paediatric Unit, LRH. Age matched healthy children aged 6-10 years were selected from similar socioeconomic backgrounds to compare the neurocognitive attainments. Neurocognitive skills were assessed using an age appropriate battery of instruments. Children older than 10 years were excluded as the assessment tools were designed only for the age range 6-10 years. Children with other co-morbidities adversely affecting their neurocognitive development were also excluded. Results: Twenty three children with CHT of age group 6-10 years were followed up in the endocrine clinic of the Professorial Paediatric Unit, LRH during the study period and 2 were excluded. Forty two age matched controls of age group 6-10 years also participated in the study. The mean age of the children was 2.42±2.59 years. The mean TSH levels at diagnosis was 43.17± 34.25mU/L. Starting dose of thyroxine in the majority was less than 10μg/kg/day. Children with CHT performed less than their peers in all age ranges and in all areas of skills. Statistically significant differences were documented in the total performance percentiles at ages of 8 (p=0.0001) and 9 years (p=0.0002). Similarly, they performed less in literacy at 8 (p=0.015) and 9 years (p=0.004), verbal performance at 8 years (p= 0.0002) and numeracy in 9 years (p=0.035). There was no significant correlation between the neurocognitive scores and age at diagnosis, initial TSH levels, thyroxine commencement dose or the number of clinic visits in the first year. Conclusions: Children with CHT of age group 6- 10 years, attending the endocrine clinic of the Professorial Paediatric Unit, LRH had significantly reduced neurocognitive skills compared to age matched controls. There was no significant correlation between the neurocognitive scores and age at diagnosis, initial TSH levels, thyroxine commencement dose or number of clinic visits in the first year.