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

Abstract

Objective: To evaluate the success rate of the National newborn screening program in maintenance of intelligent quotient (IQ) of children with congenital hypothyroidism in Iran.Design: Retrospective cohort study. Methods:The 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.Results: Mean 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. Conclusion:Although mean IQs of CH children was lower than their controls, IQ of all treated CH cases were close to the healthy children.Keywords: Management, Neonatal screening, Outcome. R R R R R E E E E E S S S S S E E E E E A A A A A R R R R R C C C C C H P H P H P H P H P AA A A A P P P P P E E E E E R R R R R C ongenital hypothyroidism (CH) is considered as one of the most important preventable causes of mental retardation in children [1]. The incidence of CH is different among neonates of various countries of the world and ranges from 1:2000 to 1:4000 [2-6], the incidence of CH in different areas of Iran is reported to vary from 1:400 to 1:1000 [7,8].In Iran, a National program of neonate screening was established from 2004-2005 [9]. In this program, thyroidstimulating hormone (TSH) is measured as a primary test, and positive tests are confirmed by serum thyroxine (T4). By the end of 2015, over 9 million neonates were screened and over 10 thousand children were diagnosed with CH and treated with levothyroxine (L-Thyroxine).The evaluation of this mass screening program, particularly from the view of maintaining the IQ of children with CH at the national level has been done [10,11], but there have been no systematic long-term follow-up studies for evaluation of intervention/treatment outcomes among hypothyroid children diagnosed by the nationwide newborn screening program in Iran. This study was done to assess the IQ of hypothyroid children diagnosed by national program of CH screening at age of 6 years, compared with healthy children in Iran. METHODSThis was a retrospective cohort study conducted in five provinces in different geographical areas of Iran. A total of 480 children in two study groups, including 240 children with CH and 240 healthy children were investigated in this comparative study. We first specified our samples based on mean difference sampl...

Physical and mental growth and development in children with congenital hypothyroidism: a case–control study

“…According to the Rahmani et al study, despite timely treatment of CH cases, but children with permanent hypothyroidism have a higher IQ deficit than transient ones. So that Children with PCH had 4 times less intelligent than children with TCH [23]. These cases indicate the necessity of performing reforms on national program of CH screening on the backgrounds of on time treatment and also supervision on its processes.…”

First Experiences with Newborn Screening for Congenital Hypothyroidism in Ulaanbaatar, Mongolia

“…This showed the largest national database on newborn screening to investigate an overall prevalence of CH of 1 per 2091 live births. The overall prevalence of primary CH in our present study was similar to the estimates of recent studies conducted in Ireland (1:2200) [ 17 ], China (1:2278) [ 12 ], the United States of America (1:2350) [ 18 ], Saudi Arabia (1:2470) [ 19 ], and Taiwan (1:1992) [ 3 ], However, similar or even higher results were found in Italy (1:1923) [ 20 ], Iran (1:1000) [ 21 ], Canada (1:1500) [ 22 ] and Srilanka (1:1652) [ 13 ].…”

Familial-Related Risks for Congenital Hypothyroidism in Iranian Newborns: A Population-Based Case-Control Study

“…All the Iranian public health centers that participate in the national screening program are responsible for newborn screening, treatment, and follow-up of children with CH. The success of CH treatment in Iran has been reported in a previous study (13).…”