Intelligence quotient in children with congenital hypothyroidism: The effect of diagnostic and treatment variables

Back ground: Considering the high prevalence of congenital hypothyroidism (CH) in Isfahan, the intelligence quotient (IQ) of children with CH and the effect of diagnostic and treatment variables on it were investigated during the CH screening program. A total of 120 children in three studied groups were studied in this comparative study the IQ score, in three subsets of verbal IQ, performance IQ and full scale IQ, of children diagnosed with transient congenital hypothyroidism (TCH) and permanent congenital hypothyroidism (PCH) was measured using revised Wechsler pre-school and primary scale of intelligence and compared with the control group. The relation between IQ score with time of treatment initiation and screening thyroid stimulating hormone (TSH) level was evaluated in all studied groups. Mean of verbal IQ, performance IQ, and full scale IQ score was significantly higher in the control group than CH patients (both permanent and transient) In PCH patients though it was not significant, there was a negative relationship between verbal IQ, performance IQ and full scale IQ and screening TSH and age of treatment initiation. In TCH patients, there was negative and significant relationship between verbal IQ (r = −0.40) and full scale IQ (r = −0.38) and age of treatment initiation (r = −0.46). Mean IQ score in both PCH and TCH patients were lower than the control group, which correlates negatively with treatment initiation time. Though CH screening and early treatment has improved the prognosis of patients, but early and high dose of treatment in children with CH is recommended.