ISSN 1662-4009 (online)

ESPE Yearbook of Paediatric Endocrinology (2022) 19 3.7 | DOI: 10.1530/ey.19.3.7

ESPEYB19 3. Thyroid Congenital hypothyroidism (3 abstracts)

3.7. Treatment of congenital hypothyroidism: comparison between L-thyroxine oral solution and tablet formulations up to 3 years of age

Vigone MC , Ortolano R , Vincenzi G , Pozzi C , Ratti M , Assirelli V , Vissani S , Cavarzere P , Mussa A , Gastaldi R , Di Mase R , Salerno M , Street ME , Trombatore J , Weber G & Cassio A



Eur J Endocrinol. 2021 Nov 30;186(1):45-52. doi: 10.1530/EJE-20-1444. PMID: 34714772

Brief Summary: This retrospective multicenter study examined the biochemical and neurocognitive outcomes of n=254 patients with congenital hypothyroidism (CH) at age 3 years, treated with either LT4 drops (n=117) or LT4 tablets (n=137). Overall, neurocognitive outcome was not different between the two treatment groups. Patients treated with LT4 drops showed lower TSH values at days 15 and 30 suggesting higher risk of overtreatment.

This study compared the effectiveness of LT4 drops to LT4 tablets on biochemical and neurocognitive outcome in patients with CH. The two treatment groups represented the whole range of CH severity (mild to severe, according to guidelines) and thyroid phenotype (athyreosis, ectopy, thyroid gland in situ). Median age at diagnosis was comparable (12 days for LT4 drops and 13 days for LT4 tablets, respectively). TSH, FT4 and LT4 mcg/kg/d were compared at 15 days, 1,3,6,12, 24, and 36 months. Those treated with LT4 drops were more likely to have TSH < 0.5 mIU/L at 1 and 6 months of age and FT4 >2.2 ng/dL at 1 month of age, indicating higher risk for overdosing on equivalent LT4 doses. Total development quotient did not differ between groups at 36 months. However, those treated with LT4 drops had lower scores at 12 months for speech, and at 36 months for eye-hand coordination.

This important study is the first large trial comparing two different LT4 preparations for the treatment of CH. Biochemical and neurocognitive outcomes at 3 years of age were comparable with relevant differences concerning risk of overdosing in the first months of life. This aspect is of clinical relevance in the light of recent data suggesting not only under- but overdosing is associated with impaired neurocognitive outcomes [1,2]. Therefore, the authors recommend a lower starting dose if using LT4 drops rather than with LT4 tablets.

References: 1. Cognitive development in congenital hypothyroidism: is overtreatment a greater threat than undertreatment? Bongers-Schokking JJ, Resing WC, de Rijke YB, de Ridder MA, de Muinck Keizer-Schrama SM. J Clin Endocrinol Metab. 2013 Nov;98(11):4499–506. doi: 10.1210/jc.2013-2175. Epub 2013 Aug 26. PMID: 23979950. 2. Long-term effects of L-thyroxine therapy for congenital hypothyroidism. Rovet JF, Ehrlich RM. J Pediatr. 1995 Mar;126(3):380–6. doi: 10.1016/s0022-3476(95)70452-3. PMID: 7869196.

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