ESPE Abstracts

Background: Congenital hypothyroidism (CH) is one of the preventable causes of intellectual disability. L-thyroxine is a drug of choice for CH treatment to preserve normal brain development and function.

Objective: to evaluate intellectual outcomes at preschool age in early treated CH.

Materials and Methods: This retrospective chart review was conducted on 27 treated children with CH identified by neonatal screening program in Thailand from 1998 to 2017. The IQ test was performed at aged 6-8 years. Clinical data including sex, birth weight, age at the initiation of L-thyroxine, level of Free T4 and TSH before treatment, initial dose of L-thyroxine, type of CH, aged at IQ test, full scale IQ, verbal IQ and performance IQ were reviewed.

Results: Of 27 CH children, 7 patients were initially early treated with L-thyroxine before aged 14 days and 20 patients were treated after aged 14 days. Initial free T4, TSH, weight at treatment and initial dose of L-thyroxine were not different between early and late treatment group. Mean full scale IQ difference between 2 groups was statistic significantly (P=0.01). However, there was no statistically significant difference in the mean of verbal IQ and performance IQ. Thyroid scan results show dyshormonogenesis (n=12), thyroid agenesis/hypoplasia (n=5), and ectopic (n=10) Mean full scale IQ in dyshormonogenesis group was more than thyroid agenesis/hypoplasia and ectopic thyroid group. We found that timing at treatment and type of CH were independent factors significantly influencing the intellectual outcome (full IQ score>90). (P=0.01)

Conclusion: Children with CH treated early after newborn screening within 14 days have better IQ score compare to CH treated after 14 days. Timing of treatment and type of CH have a role in neurodevelopment and intellectual outcome in CH children.