Incidence of Congenital Hypothyroidism Over 37 Years in Ireland

Abstract

BACKGROUND AND OBJECTIVES: Congenital hypothyroidism (CHT) is one of the most common preventable causes of learning disability. Newborn screening with whole-blood thyroidstimulating hormone measurements was introduced in the Republic of Ireland in 1979 and is coordinated from a single center with an unchanged protocol since its inception. Our objective in this study was to describe the incidence of CHT in the Republic of Ireland over the past 37 years in the context of a complete national population and an unchanged screening protocol. METHODS:The newborn screening records of all individuals who were diagnosed with CHT between 1979 and 2016 were reviewed. Infants with positive screening results had a whole-blood thyroid-stimulating hormone value of ≥15 mU/L at 72 to 120 hours of life; values of 8 to 15 mU/L required a repeat whole-blood screening test.

Prevalencia al nacimiento de hipotiroidismo congénito

“…El aumento de la prevalencia al nacimiento de hipotiroidismo congénito es un hecho que se ha observado en muchos países y regiones del mundo y algunos investigadores han encontrado prevalencias de hasta 6.5 x 10,000 recién nacidos en los últimos 3 años (Cuadro 4). [21][22][23][24][25][26] Estudios internacionales demuestran que los grupos poblacionales que tienen mayor prevalencia de hipotiroidismo congénito son los asiáticos y los hispánicos, entre los que se encuentran clasificadas aquellas personas provenientes de América Latina y los que tienen menores prevalencias son los afrodescendientes. 17 Las causas del aumento del hipotiroidismo congénito son desconocidas.…”

Determining Reference Ranges for Total T4 in Dried Blood Samples for Newborn Screening

“…Other factors that could affect tT 4 concentrations are sex, ethnicity, seasonality, age at sampling, and other factors, such as TBG and albumin.It is important to distinguish the two main types of CH: primary CH (T-CH) and central CH (C-CH). Primary congenital hypothyroidism, also called thyroidal hypothyroidism, affects approximately 1:2000-1:4000 newborns [5]. It is caused by a lack of thyroid hormone production, namely T 4 and T 3 , mostly due to a dysfunctional thyroid gland (thyroid dysgenesis or dyshormonogenesis).Secondary CH, also called hypopituitary CH or central CH, is not of thyroidal origin, but rather of pituitary origin.…”

“…This means that the problem lies within the production of TSH. C-CH is a much rarer cause of hypothyroidism, with a prevalence of 1:20,000 to 1:80,000 in the general population [5,6]. Among infants with C-CH, the TSH values are more U-shaped, which means that TSH measurements can result in being either low, normal, or increased.…”

“…It is important to distinguish the two main types of CH: primary CH (T-CH) and central CH (C-CH). Primary congenital hypothyroidism, also called thyroidal hypothyroidism, affects approximately 1:2000-1:4000 newborns [5]. It is caused by a lack of thyroid hormone production, namely T 4 and T 3 , mostly due to a dysfunctional thyroid gland (thyroid dysgenesis or dyshormonogenesis).…”

Clinical profile of congenital hypothyroidism identified through new-born screening: a retrospective observational study

“…With the increasing neonatal screening coverage all over the world, the incidence of CH is also increasing. 2 The incidence rate of CH varies by geographic location and ethnicity. 3 There is also significant difference in the etiology of CH based on the population being studied.…”