Congenital hypothyroidism in different cities of the Isfahan province: A descriptive retrospective study

Considering the high prevalence rate of congenital hypothyroidism CH in Iran, an epidemiological study in each region would be helpful in understanding the etiology of the disorder and providing preventative strategies in this field. This study aims to determine the prevalence of CH in different cities of the Isfahan province.

This descriptive and retrospective study was conducted among 918 primarily diagnosed CH neonates, who have been identified through the neonatal screening program from 2009 to 2015. At the age of ≥3 years, treatment was discontinued for 4 weeks, and T4 and thyroid-stimulating hormone were measured. Permanent (PCH) or transient (TCH) was determined from the results of the thyroid function tests.

From 389,101 screened neonates, 918 were diagnosed with primary CH. The overall prevalence rate of CH was 2.36 in 1000 live birth (ranged 1.58-7.22 in 1000 live birth in different cities). The highest prevalence rate of CH was reported in Ardestan, Khansar, Golpaygan, and Nain cities with prevalence rate of 4.86-7.22 in 1000 live birth and lowest prevalence occurring in Fereydan, Shahreza, Isfahan, and Mobarakeh cities with prevalence rate of 1.58-1.89 in 1000 live birth. In 392 cases which reached to 3 years of age, the rate of TCH was 47.45%. In Chadegan, Natanz, Fereydunshahr, Shahinshahr, Najafabad, Dehaghan, Borkhar, and Mobarakeh, the prevalence of PCH was <50%.

The current findings indicate that the incidence rate of both PCH and TCH are high in Isfahan province with significant variability in different cities which could be due to the role of different genetic, prenatal, and different environmental factors. These epidemiological data could be used as baseline date to design more etiological studies.