A 7-year study on the prevalence of congenital hypothyroidism in northern Iran.

Background: Congenital hypothyroidism (CH) is one of the most common congenital endocrine disorders.The present study determined the prevalence and demographic characteristics of congenital hypothyroidism in the north of Iran.

Objective: To determine the prevalence of congenital hypothyroidism based on transient and permanent types with demographic characteristics in Mazandaran province in northern Iran.

Methods: This retrospective descriptive survey analyzed the medical records of children with primary diagnosis of CH in health centers in all cities of Mazandaran Province between June 2009 and March 2016. To compare the study groups (CH type) in terms of quantitative and qualitative variables, the t-test and Chi-square test were used, respectively using the SPSS22. P-value <0.05 was considered as significant.

Results: Of 269,088 infants screened during the study period, 548 infants with primary congenital hypothyroidism were identified (a prevalence of 1 per 491 births) and congenital hypothyroidism was definitively diagnosed in 389 children (a prevalence of 1 per 453 births); of them, 169 had permanent CH (a prevalence of 1 per 1043 births) and 220 had transient CH (a prevalence of 1 per 801 births). The female to male ratio in the permanent congenital hypothyroidism group was higher than that in the transient congenital hypothyroidism group (p=0.08). The family relationship between mother and father was stronger in the permanent congenital hypothyroidism group than in the transient congenital hypothyroidism group (p=0.03).

Conclusion: These findings show that congenital hypothyroidism is more prevalent in the north of Iran than in other areas of Iran; the prevalence of transient CH is particularly higher than permanent CH.