Evaluation of neurodevelopment of children with congenital hypothyroidism by the Denver Developmental Screening Test.

Background: Thyroid hormones are essential for growth and brain development in childhood. Although congenital hypothyroidism (CH) is the most common reason for mental retardation, normal neurological development can be achieved through early and effective treatment. The aim of the present study was to evaluate the neurological development of CH patients aged 24-56 months.

Methods: The study included a total of 116 healthy control subjects and 112 patients aged 24-56 months who were diagnosed with CH during the neonatal period and were being followed up at the Pediatric Endocrinology Department, Keçiören Training and Research Hospital, between 2012 and 2015. Demographics and clinical data of interventions and outcomes were retrieved for each patient. Statistical analysis was performed using an unpaired Student's t-test to compare means and χ2-analysis to compare proportions.

Results: There were no significant differences between the CH and control groups with respect to gestational age, birth weight, height standard deviation scores (HSDS) and body weight standard deviation scores (BWSDS) (p>0.05). When the groups were compared according to the Denver Developmental Screening Test (DDST), no significant differences were found in terms of personal-social, fine motor skills, or language development (p=0.325, p=0.087 and p=0.636, respectively). However, a significant difference was found between the two groups with respect to gross motor development and the result of the DDST (p=0.001). No statistical difference was found between the control and patient groups on the day of starting treatment but the number of patients with an abnormal result in the DDST starting treatment at >15 days was found to be significantly higher than the number of patients starting treatment ≤15 days. No associations were found between the DDST results of the CH group and the following factors: initial L-thyroxine (LT4) level, initial LT4 dose and the onset of treatment.

Conclusions: The findings of this study indicate that the DDST results in patients with CH are generally good. Initiating treatment immediately after diagnosis and during the first days of life is absolutely imperative. However, in contrast to timing, we could not find strong evidence for determining the precise optimal dosage of LT4 to initiate treatment in children diagnosed with CH. Both the American Academy of Pediatrics and the European Society for Pediatric Endocrinology recommend 10-15 μg/kg/day as the initial dose.