Intellectual development in preschool children with early treated congenital hypothyroidism

• Published in: Annals of pediatric endocrinology & metabolism Vol. 22; no. 2; pp. 102 - 107
• Main Authors: Seo, Min Kyoung, Yoon, Jong Seo, So, Chul Hwan, Lee, Hae Sang, Hwang, Jin Soon
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society of Pediatric Endocrinology 01.06.2017; Korean Society of Pediatric Endocrinology; 대한소아내분비학회
• Subjects: Congenital; Hypothyroidism; Intellectual disability; Original; Synthyroid; 소아과학; Intellectual disability; Congenital; Hypothyroidism; Synthyroid
• ISSN: 2287-1012; 2287-1292
• DOI: 10.6065/apem.2017.22.2.102

Delayed treatment of congenital hypothyroidism (CH) is a common cause of mental retardation. The aim of the present study was to evaluate intellectual outcomes in preschool children with treated CH. We retrospectively reviewed the clinical records of 43 children (age range: 13 to 60 days of life; 22 girls and 21 boys) diagnosed with CH. Children aged 5 to 7 years were examined using the Korean Wechsler Intelligence Scale for Children or the Korean Wechsler Preschool and Primary Scale of Intelligence. The patients started treatment between 13 and 60 days of age. The mean intelligence quotient (IQ) of patients tested at age 5 to 7 years was 103.14±11.68 (IQ range: 76-126). None had intellectual disability (defined as an IQ <70). Twenty-one subjects were treated with a low dose (6.0-9.9 µg/kg/day) and 22 with a high dose of levothyroxine (10.0-16.0 µg/kg/day). There was no significant difference in the mean full-scale IQ (FSIQ), verbal IQ (VIQ), and performance IQ (PIQ) scores between the 2 groups. FSIQ, PIQ, and VIQ scores were not significantly correlated with initial dose of L-T4, initial fT4, age at treatment in multivariate analysis. IQ scores of subjects with early treated CH diagnosed through a neonatal screening test were within normal range, regardless of etiology, thyroid function, initial dose of levothyroxine, and age at start of treatment.