Ann Pediatr Endocrinol Metab.  2017 Jun;22(2):102-107. 10.6065/apem.2017.22.2.102.

Intellectual development in preschool children with early treated congenital hypothyroidism

• Seo MK
• Yoon JS
• So CH
• Lee HS
• Hwang JS

• KMID: 2383904
• DOI: http://doi.org/10.6065/apem.2017.22.2.102

Abstract

PURPOSE
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.
METHODS
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.
RESULTS
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.
CONCLUSION
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.

Keyword

Congenital; Hypothyroidism; Intellectual disability; Synthyroid

MeSH Terms

Child
Child, Preschool*
Congenital Hypothyroidism*
Female
Humans
Hypothyroidism
Infant, Newborn
Intellectual Disability
Intelligence
Multivariate Analysis
Neonatal Screening
Reference Values
Retrospective Studies
Thyroid Gland
Thyroxine
Thyroxine

Figure

• 

  Fig. 1 Flow diagram of subjects who were diagnosed with congenital hypothyroidism. IQ, intelligence quotient.

Reference

1. American Academy of Pediatrics. Section on Endocrinology and Committee on Genetics, American Thyroid Association. Public Health Committee, Lawson Wilkins Pediatric Endocrine Society. Rose SR, Brown RS, Foley T, et al. Update of newborn screening and therapy for congenital hypothyroidism. Pediatrics. 2006; 117:2290–2303. PMID: 16740880.

2. Rovet JF. The role of thyroid hormones for brain development and cognitive function. Endocr Dev. 2014; 26:26–43. PMID: 25231442.

3. Kreisner E, Schermann L, Camargo-Neto E, Gross JL. Predictors of intellectual outcome in a cohort of Brazilian children with congenital hypothyroidism. Clin Endocrinol (Oxf). 2004; 60:250–255. PMID: 14725688.

4. Boileau P, Bain P, Rives S, Toublanc JE. Earlier onset of treatment or increment in LT4 dose in screened congenital hypothyroidism: which as the more important factor for IQ at 7 years? Horm Res. 2004; 61:228–233. PMID: 15115051.

5. Salerno M, Militerni R, Bravaccio C, Micillo M, Capalbo D, Di MS, et al. Effect of different starting doses of levothyroxine on growth and intellectual outcome at four years of age in congenital hypothyroidism. Thyroid. 2002; 12:45–52. PMID: 11838730.

6. Huo K, Zhang Z, Zhao D, Li H, Wang J, Wang X, et al. Risk factors for neurodevelopmental deficits in congenital hypothyroidism after early substitution treatment. Endocr J. 2011; 58:355–361. PMID: 21467693.

7. Bongers-Schokking JJ, Resing WC, de Rijke YB, de Ridder MA, de Muinck Keizer-Schrama SM. Cognitive development in congenital hypothyroidism: is overtreatment a greater threat than undertreatment. J Clin Endocrinol Metab. 2013; 98:4499–4506. PMID: 23979950.

8. Kwak K, Park H, Kim C. The manual for the Korean WISC-III. Seoul: Special Education Publishing Co.;2002.

9. Kwak K, Park H, Kim C. A study for the standardization of Korean WISC-3 (1). Korean J Dev Psychol. 2002; 15:19–33.

10. Park H, Kwak K, Park K. Korean-Wechsler preschool and primary scale of intelligence. Seoul: Special Education Publishing Co.;1995.

11. Wechsler D. Wechsler preschool and primary scale of intelligence. San Antonio (TX): Psychological Corp.;1989.

12. Tuhan H, Abaci A, Cicek G, Anik A, Catli G, Demir K, et al. Levothyroxine replacement in primary congenital hypothyroidism: the higher the initial dose the higher the rate of overtreatment. J Pediatr Endocrinol Metab. 2016; 29:133–138. PMID: 26244672.

13. Rastogi MV, LaFranchi SH. Congenital hypothyroidism. Orphanet J Rare Dis. 2010; 5:17. PMID: 20537182.

14. Dimitropoulos A, Molinari L, Etter K, Torresani T, Lang-Muritano M, Jenni OG, et al. Children with congenital hypothyroidism: long-term intellectual outcome after early high-dose treatment. Pediatr Res. 2009; 65:242–248. PMID: 18787501.

15. Kim S, Lee DH. Intellectual outcome in children with congenital hypothyroidism treated from early life. J Korean Soc Pediatr Endocrinol. 2006; 11:45–49.

16. Léger J, Olivieri A, Donaldson M, Torresani T, Krude H, van Vliet G, et al. European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism. Horm Res Paediatr. 2014; 81:80–103. PMID: 24662106.

17. Rovet JF, Ehrlich RM. Long-term effects of L-thyroxine therapy for congenital hypothyroidism. J Pediatr. 1995; 126:380–386. PMID: 7869196.

18. Bongers-Schokking JJ, de Muinck Keizer-Schrama SM. Influence of timing and dose of thyroid hormone replacement on mental, psychomotor, and behavioral development in children with congenital hypothyroidism. J Pediatr. 2005; 147:768–774. PMID: 16356429.

19. Ng SM, Anand D, Weindling AM. High versus low dose of initial thyroid hormone replacement for congenital hypothyroidism. Cochrane Database Syst Rev. 2009; (1):CD006972. PMID: 19160309.

20. LaFranchi SH, Austin J. How should we be treating children with congenital hypothyroidism? J Pediatr Endocrinol Metab. 2007; 20:559–578. PMID: 17642417.

21. Tillotson SL, Fuggle PW, Smith I, Ades AE, Grant DB. Relation between biochemical severity and intelligence in early treated congenital hypothyroidism: a threshold effect. BMJ. 1994; 309:440–445. PMID: 7920127.

22. Hsiao PH, Chiu YN, Tsai WY, Su SC, Lee JS, Soong WT. Intellectual outcome of patients with congenital hypothyroidism detected by neonatal screening. J Formos Med Assoc. 2001; 100:40–44. PMID: 11265259.

23. Hulse JA. Outcome for congenital hypothyroidism. Arch Dis Child. 1984; 59:23–29. PMID: 6198974.

24. MacFaul R, Grant DB. Early detection of congenital hypothyroidism. Arch Dis Child. 1977; 52:87–88. PMID: 836070.