Newborn screening for congenital hypothyroidism and re-screening at two weeks of life in infants born to mothers with thyroid diseases

Gaia Vincenzi; Vigone Maria Cristina; Paolo Cavarzere; Lorella Palma; Marta Camilot; Francesca Teofoli; Riccardo Amicosante; Daniela Rotondi; Cristina Cereda; Laura Cappelletti; Luisella Alberti; Graziano Barera; Angelis Simona De; Antonella Olivieri

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ESPE Abstracts (2024) 98 P1-207

ESPE2024 Poster Category 1 Thyroid 2 (9 abstracts)

Newborn screening for congenital hypothyroidism and re-screening at two weeks of life in infants born to mothers with thyroid diseases.

Gaia Vincenzi ¹ , Maria Cristina Vigone ¹ , Paolo Cavarzere ² , Lorella Palma ² , Marta Camilot ² , Francesca Teofoli ² , Riccardo Amicosante ³ , Daniela Rotondi ³ , Cristina Cereda ⁴ , Laura Cappelletti ⁴ , Luisella Alberti ⁴ , Graziano Barera ¹ , Simona De Angelis ³ & Antonella Olivieri ³

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¹IRCCS Ospedale San Raffaele, Milano, Italy. ²Azienda Ospedaliera Universitaria Integrata di Verona, Verona, Italy. ³Istituto Superiore di Sanità, Roma, Italy. ⁴Ospedale dei Bambini "V. Buzzi", Milano, Italy

Background: The benefit of re-screening at 15 days of life in infants born to mothers with thyroid diseases (TD+) is a debated issue. In Italy, all the 16 newborn screening (NBS) laboratories use TSH measurement on dried blood spot as primary screening test for primary congenital hypothyroidism (CH) and adopt a 2-screen strategy in special categories of infants at risk of delayed TSH rise (preterm birth, admission to NICU, extra-thyroidal malformations, twinning). Nevertheless, only 2 NBS laboratories adopt a 2-screen strategy also in infants born to mothers TD+: the NBS Laboratory in Milan-Lombardy region (Lab-MI), which uses a mandatory protocol, and the NBS Laboratory in Verona-Veneto region (Lab-VR) which uses a recommended protocol. In both laboratories a differential TSH cutoff is adopted (10 mIU/L at 1st screen, 5 mIU/L at 2nd screen). This study aimed at verifying whether a 2-screen strategy in infants born to mothers TD+ can identify additional cases of primary CH.

Methods: Data collected in the Italian National Registry of Infants with Congenital Hypothyroidism (INRICH) in the period 2010-2019 were analysed.

Results: The INRICH data showed that among the 2,216 infants diagnosed with primary CH in the period of observation, n = 326 were born to mothers TD+ (14.7%). In these 326 infants, 74% showed normal/hyperplastic thyroid and 26% thyroid dysgenesis. When only infants screened and diagnosed in Lombardy and Veneto regions were considered (n = 1171) the prevalence of infants born to mothers TD+ increased to 18.7% (218/1171). In these regions, 90 of the 218 infants born to mothers TD+ (41.3%) were identified at the 2nd screen because of the presence of risk factors for delayed TSH rise. However, 37 of 218 (17.0%) showed maternal TD+ as the only risk factor for the 2nd screening test (all term infants >=37 weeks; no extrathyroidal malformations; no twins, no NICU admission). In these 37 infants, the median (Q1, Q3) TSH value at 1st screen was 5.9 (4.4, 7.1) mIU/L, 8.1 (6.0, 11.8) mIU/L at 2nd screen, while at the diagnosis median serum TSH was 25.0 (16.0, 44.7) mUI/L and the mean +SD value of FT4 was 1.1 + 0.3 ng/dL.

Conclusions: The INRICH data suggest that infants born to mothers TD+ may show a delayed rise of TSH and the 10-years of two Italian NBS laboratories indicates that a 2-screen strategy adopting differential TSH cutoffs may be useful to identify additional cases of primary CH.