Physical growth and intellectual function of children with congenital hypothyroidism: An observational study

Introduction: Congenital hypothyroidism (CH) is an important preventable cause of mental retardation. Objectives: To assess growth parameters and the developmental outcome of children with permanent CH on follow up. Method: This was a hospital-based observational study done in the paediatric endocrinology clinic of a tertiary care hospital in South India. The study population included all children with permanent CH aged 5-18 years attending the clinic from March 2017 to March 2018. Weight, height and head circumference of children were measured and the body mass index (BMI) was calculated. Ultrasonography (USG) of the thyroid was done for all patients and structural abnormalities of the thyroid (aplasia, hypoplasia or ectopic gland) were taken as dysgenesis. If USG had normal thyroid it was taken as dyshormonogenesis. Intelligence quotient (IQ) assessment was done by a clinical psychologist. Results: There were 35 children with CH enrolled in the study. Of this, 17 (49%) were diagnosed on or before 6 months of age and 18 (51%) after 6 months of age; 24 (69%) had thyroid dysgenesis and 11 (31%) had dyshormonogenesis; 4 had severe stunting and 5 were obese. Among the 17 children diagnosed on or before 6 months of age, 12 (70.6%) had normal intelligence and 5 (29.4%) had IQ <85 whereas among the 18 children diagnosed after 6 months of age 6 (33%) had normal intelligence and 12 (66%) had IQ <85, which was statistically significant (p=0.028). There were no significant differences between early and late diagnosis groups in other parameters like developmental delay, stunting and BMI. Among 24 children with dysgenesis of thyroid gland, 14 (58%) had IQ <85 whereas among 11 children with dyshormonogenesis, 3 (37.5%) had IQ <85. This was not statistically significant (p=0.08). Conclusions: In this study, a statistically significantly larger proportion of children diagnosed on or before 6 months of age had normal intelligence compared to children diagnosed after 6 months of age. There were no significant differences between early and late diagnosis groups in other parameters like developmental delay, stunting and BMI. Sri Lanka Journal of Child Health, 2023: 52(2): 148-154