The use of L-T4 as liquid solution improves the practicability and individualized dosage in newborns and infants with

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J H von Heppe1, H Krude, D L'Allemand

  • 1Charité, Humboldt-Universität, Pediatric Endocrinology, Otto-Heubner Centrum für Kinder- und Jugendmedizin, Berlin, Germany.

Journal of Pediatric Endocrinology & Metabolism : JPEM
|August 11, 2004
PubMed

Insights

Initial levothyroxine (LT4) dosage for congenital hypothyroidism (CH) in newborns is crucial for rapid TSH normalization. Liquid LT4 effectively treats CH, with higher initial doses reflecting increased early-life thyroid hormone needs.

Area of Science:

  • Pediatrics
  • Endocrinology
  • Neonatal Care

Background:

  • Congenital hypothyroidism (CH) requires timely thyroid hormone replacement therapy.
  • Initial dosage recommendations for levothyroxine (LT4) in CH vary.
  • Evaluating liquid LT4 formulations is important for neonatal treatment.

Purpose of the Study:

  • To assess the feasibility of using liquid LT4 for CH treatment in newborns.
  • To determine the optimal initial LT4 dosage for achieving target TSH levels.
  • To correlate initial dosage with TSH normalization time and developmental outcomes.

Main Methods:

  • Administered liquid LT4 to 28 newborns with primary CH.
  • Monitored TSH, T3, T4, free T3, and free T4 levels during treatment.
  • Assessed neurodevelopment using the Griffith test after 2 years.

Main Results:

  • Median initial LT4 dose was 12.3 microg/kg/d, decreasing to 5 microg/kg/d by 9 months.
  • TSH normalization (< or =6 mU/l) occurred within a median of 2 weeks.
  • Higher initial doses (12.7 microg/kg) led to faster TSH normalization (1 week) compared to lower doses (10.1 microg/kg, 2 months).

Conclusions:

  • Newborns with CH require prompt TSH normalization (1-2 weeks).
  • Liquid LT4 is effective, and initial dosage requirements are not lower than with tablets.
  • Higher initial LT4 doses are necessary due to increased neonatal thyroid hormone demand.
Abstract

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