One in every 2,000 newborns has congenital hypothyroidism (CH). If not recognized and promptly treated, CH leads to permanent intellectual disability.
While newborn screening (NBS) for CH and other conditions has been performed since the 1950s, knowledge regarding diagnosis and therapy continues to improve.
An updated AAP clinical report from the AAP Section on Endocrinology, AAP Council on Genetics, Pediatric Endocrine Society and American Thyroid Association provides recommendations, with expanded discussion and literature evidence in a companion technical report.
The reports, Congenital Hypothyroidism: Screening and Management, are available at https://doi.org/10.1542/peds.2022-060419 and https://doi.org/10.1542/peds.2022-060420 and will be published in the January issue of Pediatrics.
CH is an inborn condition in which thyroid hormone levels are insufficient for the normal development and function of body tissues. CH is one of the most common preventable causes of intellectual disability worldwide.
Recommendations
The reports include the following primary recommendations:
All newborns globally should undergo NBS. Screening for readily treatable conditions is performed in only about 30% of all newborns globally. Treatment of all the conditions identified by NBS would save billions of dollars globally over infants’ lifespans. The clinical report outlines and discusses details of the NBS process.
If the NBS for CH is abnormal, the infant needs to be seen promptly for a confirmatory test so that thyroid hormone replacement can be started. However, many results can reveal gray areas, including mild thyrotropin (TSH) elevation, TSH elevation with a normal free thyroxine (FT4), twin birth, newborn illness, preterm birth, Down syndrome, central hypothyroidism, maternal thyroid conditions and antibodies, and transient CH. The clinical report includes an algorithm for decision-making, along with discussion of diagnostic dilemmas and whether to perform imaging or genetic testing.
If NBS thyroid tests are normal, consider hypothyroidism if the child has clinical signs and symptoms suggestive of CH, including large posterior fontanelle, large tongue, umbilical hernia, prolonged jaundice, constipation, lethargy and hypothermia.
Imaging and/or genetic testing are options when results would alter clinical management. Initiation of thyroid hormone therapy should not be delayed in order to perform these tests.
Thyroid hormone replacement with levothyroxine (T4) should be initiated as soon as the diagnosis of CH has been confirmed. The reports show that triiodothyronine (T3) should not be used, since the brain requires cerebrospinal fluid concentrations of T4 (which then are converted in the cells to T3).
Follow a regular schedule of endocrine clinic follow-up and thyroid tests (every one to two months in the first six months of life, every three months until age 3 years, then every six to 12 months thereafter). Testing regularly ensures that doses are up to date to achieve a TSH in the target range (0.5-2.0 milliunits per liter). Consistent thyroid hormone therapy with serum TSH in the target range is essential to allow the child to reach his or her neurologic potential and optimal physical growth.
Since transient hypothyroidism may be present, many children with CH should undergo re-evaluation of their endogenous thyroid function (after discontinuing thyroid hormone therapy for a month) at age 3 years. If TSH is elevated again, long-term therapy should be resumed.
Overall, children with CH have benefited greatly from NBS programs combined with clinicians’ efforts to keep patients on optimal thyroid hormone therapy. Many of those with CH now are normally functioning adults without permanent intellectual disability.
Dr. Rose is a lead author of the clinical and technical reports.
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