An updated evidence-based guideline supports global neonatal screening for congenital hypothyroidism to optimize detection, diagnosis, treatment and follow-up of children with the condition.
Despite the benefits of neonatal screening, 70% of infants worldwide are born in areas that do not have access to neonatal screening, Paul van Trotsenburg, MD, PhD, professor of pediatric endocrinology at the University of Amsterdam, and colleagues wrote in the guideline, published in Thyroid. Many of these infants are born in areas of endemic iodine deficiency, placing them at increased risk for thyroid hormone deficiency, the researchers wrote.
“This update of the consensus guidelines on congenital hypothyroidism recommends worldwide neonatal screening and appropriate diagnostics — including genetics — to assess the cause of both primary and central hypothyroidism,” van Trotsenburg said in a press release. “The expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up, including laboratory testing and dose adjustments, to keep thyroid levels in their target ranges, timely assessments of the need to continue treatment, attention for neurodevelopmental and neurosensory function and, if necessary, consulting other health professions, and education of the child and family about congenital hypothyroidism.”
The recommendations include the various neonatal screening approaches for congenital hypothyroidism, as well as guidance for genetic screenings, diagnostics, treatment and prognosis of both primary and central congenital hypothyroidism.
The expert panel made several recommendations:
- Screening for congenital hypothyroidism should be introduced worldwide; the most sensitive test for detecting primary congenital hypothyroidism is measurement of thyrotropin.
- When congenital hypothyroidism is diagnosed, immediately initiate correctly dosed levothyroxine treatment and frequent follow-up, including laboratory testing, to keep thyroid hormone levels in their target ranges.
- Conduct timely assessments of the need to continue treatment, assess for neurodevelopment and neurosensory functions, and, if necessary, consult other health professionals, along with providing education for the child and family about congenital hypothyroidism.
- All individuals with congenital hypothyroidism are entitled to a well-planned transition of care from pediatrics to adult medicine.
“This consensus guidelines update should be used to further optimize detection, diagnosis, treatment and follow-up of children with all forms of congenital hypothyroidism in the light of the most recent evidence,” the researchers wrote. “It should be helpful in convincing health authorities of the benefits of neonatal screening for congenital hypothyroidism. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.”
The guideline, an update to expert recommendations published in 2014, is endorsed by the American Thyroid Association, the European Society for Paediatric Endocrinology and the European Society of Endocrinology.
Perspective
In 1972, Jean Dussault, MD, a thyroidologist working at Laval University in Quebec City, Canada, developed the first mass screening to diagnose congenital hypothyroidism in neonates. He measured thyroxine in dried blood spots, routinely collected on filter paper in the province of Quebec for screening of phenylketonuria and tyrosinemia. Of 30,000 samples collected from newborns, four were found to have congenital hypothyroidism. Since then, thyroid-stimulating hormone became the preferred initial screening test, now routinely used in most counties in the world, except for those with poor economies and in remote areas.
In the March issue of Thyroid, the ENDO-European Reference Network published an updated guideline for the screening, diagnosis and treatment of congenital hypothyroidism. An earlier version, in which several of the current authors participated, was published in 2014. The current publication is more extensive, provides more references and, more importantly, contains three tables that list a total 39 genes found to be involved in the cause of congenital hypothyroidism. This was made possible by the development of more efficient and considerably less costly next-generation and whole-exome sequencing (NGS and WES), advancing our knowledge about the etiology of congenital hypothyroidism, allowing proper counseling and, in some instances, providing prenatal diagnosis and even prenatal treatment.
In the first paragraph of the introduction, the authors define congenital hypothyroidism as “dysfunction … resulting in insufficient thyroid hormone production … but also to impaired thyroid hormone action.” However, the latter cause of congenital hypothyroidism is not discussed further. This is undoubtedly because current methods of neonatal screening do not detect defects of thyroid hormone cell transport, metabolism and action.
With the introduction of liquid chromatography-tandem mass spectrometry in routine clinical laboratories, it is anticipated that simultaneous measurement of T4, T3 and reverse T3 in dried blood spots will allow the identification of these conditions. This will not only provide more accurate information about their prevalence, but also allow for early intervention that is so crucial in the treatment of congenital hypothyroidism.
Samuel Refetoff, MD
Frederick H. Rawson Professor in Medicine
Professor of Pediatrics and Committee on Genetics Director of the Endocrinology Laboratory and The Thyroid Study Unit
The University of Chicago
ARYAN'S BLOG 