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Establishing a reference range for triiodothyronine levels in preterm infants

Ki Won Oh1, Mi Sung Koo2, Hye Won Park3

  • 1Department of Pediatrics, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea.

Early Human Development
|August 25, 2014
PubMed

Insights

Establishing a reference range for triiodothyronine (T3) in preterm infants is crucial. This study found T3 levels increase with gestational age, postmenstrual age, and postnatal age, aiding in normal level determination.

Area of Science:

  • Neonatal endocrinology
  • Pediatric thyroidology

Background:

  • Thyroid dysfunction is linked to complications in preterm infants.
  • Current thyroid hormone replacement lacks proven benefits due to undefined reference ranges.

Purpose of the Study:

  • To establish a reference range for triiodothyronine (T3) levels at 1-month postnatal age (PNA) in preterm infants.

Main Methods:

  • Retrospective analysis of thyroid function tests (TFTs) from preterm infants (gestational age <35 weeks).
  • Examined relationships between T3, TSH, fT4, birth weight, GA, PMA, and PNA.
  • Analyzed fT4 to T3 conversion using the T3/fT4 ratio.

Main Results:

  • Analyzed 464 TFTs from 266 infants; excluded 65 with thyroid dysfunction.
  • T3 levels correlated positively with fT4, birth weight, GA, PMA, and PNA, but not TSH.
  • Average T3 at 1 month PNA was 72.56 ± 27.83 ng/dL, varying significantly by GA.

Conclusions:

  • Low T3 and fT4 levels in preterm infants may be normal, increasing with GA, PMA, and PNA.
  • The established reference range requires further study for thyroid hormone replacement therapy confirmation.
Abstract

Keywords:
Premature infantsThyroid function testTriiodothyronine

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