Intelligence Quotient at the Age of Six years of Iranian Children with Congenital Hypothyroidism

Abstract

ObjectiveTo evaluate the success rate of the National newborn screening program in maintenance of intelligent quotient (IQ) of children with congenital hypothyroidism in Iran.DesignRetrospective cohort study.MethodsThe IQ scores, in three subsets of verbal, non verbal (Performance) and full scale IQ, of 240 children diagnosed with Transient congenital hypothyroidism (TCH) and Permanent congenital hypothyroidism (PCH), from 5 provinces in 5 different geographical areas of Iran, were measured at the age of 6 years using revised Wechsler pre school and primary scale of intelligence and compared with 240 healthy children. We used independent sample t test and two-way ANOVA for data analysis.ResultsMean of verbal, performance, and full scale IQ scores were lower in the CH cases (permanent and transient) than the control group. Most of the IQ differences in two studied groups related to the PCH cases (P=0.005). Mean difference of IQs between children in the two groups in Yazd province (center of Iran) was higher than other provinces, and they also had significantly lower IQ than their control (healthy) children (P=0.001). No treated child had IQ<70.ConclusionAlthough mean IQs of CH children was lower than their controls, IQ of all treated CH cases were close to the healthy children.