Elsevier

The Journal of Pediatrics

Volume 205, February 2019, Pages 77-82
The Journal of Pediatrics

Original Articles
Optimal Timing of Repeat Newborn Screening for Congenital Hypothyroidism in Preterm Infants to Detect Delayed Thyroid-Stimulating Hormone Elevation

https://doi.org/10.1016/j.jpeds.2018.09.044Get rights and content

Objectives

To evaluate the timing of a delayed rise in thyroid-stimulating hormone (TSH) levels in preterm infants with congenital hypothyroidism, and to determine whether cases of congenital hypothyroidism would be missed by using current consensus guidelines of repeat screening at approximately 2 weeks of age or 2 weeks after the first screening.

Study design

The study was performed over a 13-year period (January 2004-December 2016). Whole-blood TSH samples were collected between 72 and 120 hours after birth. Repeat samples were collected weekly in preterm infants until the infant was term-corrected (37 weeks' gestation). Patients were followed up to determine whether congenital hypothyroidism was permanent or transient.

Results

Twenty-seven (50.9%) preterm infants born at <33 weeks of gestation who were diagnosed with congenital hypothyroidism had delayed TSH elevation and would not have been detected on first newborn screen. Twelve of these infants (40.7%) with delayed TSH elevation had decompensated hypothyroidism at diagnosis (free thyroxine [FT4] <10 pmol/L), and 4 had severe congenital hypothyroidism (FT4 <5.5 pmol/L) at diagnosis. If screening had been repeated only at 2 weeks of life, 13 infants (48%) with delayed TSH elevation would not have been identified. Of the 27 infants with delayed TSH elevation, 6 (22%) have permanent congenital hypothyroidism, and another 12 will be reevaluated at age 3 years.

Conclusion

Repeat screening for congenital hypothyroidism in preterm infants is necessary to avoid missing cases of congenital hypothyroidism with delayed TSH elevation. Repeat screening once at 2 weeks of life will miss infants with delayed TSH elevation and decompensated permanent congenital hypothyroidism.

Section snippets

Methods

The Ethics Committee of the Children's University Hospital, Temple St approved this study. The population-based, prospective records of the Republic of Ireland's National Newborn Bloodspot Screening Program for congenital hypothyroidism, coordinated from the Children's University Hospital, Temple Street were reviewed.

Screening for congenital hypothyroidism in the Republic of Ireland consists of collection of whole-blood samples on filter paper following a heel-prick between 72 and 120 hours

Results

Between January 2004 and December 2016, a total of 898 424 infants were screened for congenital hypothyroidism in the Republic of Ireland, and of these, 586 infants were treated for congenital hypothyroidism (incidence, 1:1533 births). A total of 53 infants (11%) were <33 weeks of gestation. Gestational age in the preterm cohort ranged from 23 to 33 weeks (median, 29 weeks), and median birth weight was 1.2 kg (range, 0.46-3.16 kg). The median serum TSH concentration at diagnosis was 78.3 mU/L

Discussion

In this study, we have found that repeat screening for congenital hypothyroidism in preterm infants is necessary to avoid missing cases of permanent and decompensated hypothyroidism. One-half of the preterm infants diagnosed with congenital hypothyroidism were not diagnosed on initial newborn screening. Among the infants with delayed TSH rise, >40% had decompensated hypothyroidism at diagnosis, and >20% had permanent congenital hypothyroidism. Along with emphasizing the importance of repeat TSH

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  • Cited by (0)

    N.M. receives support from The Children's Fund for Health, Children's University Hospital, Temple Street, Dublin. The authors declare no conflicts of interest.

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