ISSN 1662-4009 (online)

ESPE Yearbook of Paediatric Endocrinology (2018) 15 13.18 | DOI: 10.1530/ey.15.13.18

Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Prevention of Metabolic Disorders Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Endocrinology and Metabolic Office, Center for Disease Control, Ministry of Health and Medical Education, Tehran, Iran


To read the full abstract: Int J Endocrinol Metab 2017; 15(3):e55451

Systematic neonatal screening for congenital hypothyroidism (CH) was first proposed by Dr Jean Dussault, a Canadian (adult) endocrinologist, in 1974. It was rapidly implemented in most high-income countries in the late 1970’s and 1980’s. Ideally, a screening program should be highly sensitive (able to correctly identify affected neonates) and highly specific (able to correctly identify non-affected neonates): the lower the specificity, the higher the recall rate.

Thanks to an increase in capacity building in pediatric endocrinology in many low-income countries and to an increasing global interest in non-communicable diseases (NCDs) such as CH, more regional or national screening programs are being planned. Based on screening programs performed mainly in high income countries, the incidence of permanent CH is estimated to be 1/3000-1/4000. However, the incidence and cause (dysgenesis vs. dyshormonogenesis) of permanent CH varies with ethnic origin. In addition, little is known on the incidence of CH in low income countries where CH screening is not yet available.

Here, Mehran et al. describe that programs recall many unaffected neonates and they summarizes the many factors that affect the recall rate, including differences in laboratory techniques, sample collection (cord blood vs. postnatal), choice of the primary marker (TSH vs. FT4), iodine deficiency or excess, human error and recall cut-off. Defining the cut-off for recall of a program is a key aspect. A high cut-off may not guarantee the recall of ALL neonates affected with permanent CH but may be sufficient to recall the most severely affected neonates who will benefit from L-thyroxine treatment for the successful prevention of mental retardation. A low cut-off value will lead to the recall of many more neonates, including those who present with mildly, permanently elevated TSH concentrations but who are not at risk for cerebral damage. This question needs to be debated when assessing the cost-benefit ratio of a neonatal CH screening.

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