Cognitive Outcomes for Congenital Hypothyroid and Healthy Children: A Comparative Study

Objective

Early diagnosis and treatment of congenital hypothyroidism (CH) and the prevention of developmental retardation is the main goal of public health national screening programs. This study compares the cognitive ability of children with CH diagnosed by neonatal screening with a healthy control group (2007) in Yazd, Iran.

Materials & Methods

In a case-controlled study, the intelligent quotient (IQ) of 40 five-year-old children with early treated CH and good compliance were evaluated by the Wechsler preschool and primary scale of intelligent test and compared to 40 healthy age and gender matched children as controls.

Results

22 boys (55%) and 18 girls (45%) in both groups were evaluated. In children with CH, 19 (47.5%) and 21 (52.5%) persons had transient and permanent hypothyroidism, respectively.

Range of TSH and T4 level at the onset of diagnosis were 11.41–81 mu/l and 1.50–14.20 μg/dl, respectively.The intelligence levels of all children with CH were within the average or normal range and IQs ranged from 91–108.

Children with CH had lower full-scale IQs (107.25 ± 2. 9 versus 110.50 ± 2.66, p=0.001), verbal IQ (106.95 ± 3.5 versus 109.90 ± 3.44, P-value=0.001) and performance IQ (106.3 ± 3.68 versus 108.87 ± 3.70) than the control group.However, no statistically significant differences were observed for mean IQ scores in permanent and transient CH.

Conclusion

Children with CH who had early treatment and good compliance had normal cognitive abilities, but may have a decreased IQ relative to the healthy control group.