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Pediatric reference intervals for thyroid hormone levels from birth to adulthood: a retrospective study

Klaus Kapelari1, Christine Kirchlechner, Wolfgang Högler

  • 1Department of Pediatric and Adolescent Medicine, Medical University of Innsbruck, Austria. klaus.kapelari@i-med.ac.at

BMC Endocrine Disorders
|November 28, 2008
PubMed

Insights

Pediatric thyroid hormone reference intervals for thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) are crucial for accurate diagnosis. This study establishes these intervals from birth to 18 years, noting significant age-related declines and sex differences in fT3.

Area of Science:

  • Endocrinology
  • Pediatric Endocrinology
  • Clinical Chemistry

Background:

  • Accurate interpretation of pediatric thyroid hormone measurements requires age- and sex-specific reference intervals.
  • Limited data exists for pediatric reference values of TSH, fT3, and fT4.
  • Reference intervals are known to be method- and population-dependent.

Purpose of the Study:

  • To establish reference intervals for serum TSH, fT3, and fT4 in children from birth to 18 years.
  • To assess potential sex differences in these thyroid hormone levels.
  • To provide updated reference data considering analytical methods and population variations.

Main Methods:

  • Retrospective analysis of 2,194 thyroid hormone tests from a pediatric population.
  • Exclusion of individuals with conditions or medications affecting thyroid function.
  • Measurement of fT3, fT4, and TSH using the Advia(R) Centaur automated immunoassay system.

Main Results:

  • Final sample sizes: 1,209 for TSH, 1,395 for fT3, and 1,229 for fT4.
  • Median concentrations of fT3, fT4, and TSH were highest in the first month of life, declining with age.
  • Males exhibited significantly greater mean fT3 concentrations than females (p < 0.001), with no sex differences found for TSH and fT4.

Conclusions:

  • Thyroid hormone levels change significantly during childhood, rendering adult reference intervals inapplicable.
  • Established reference intervals differ from previous studies, potentially due to analytical methods, population characteristics, or geographic factors.
  • These findings underscore the importance of age- and sex-specific reference intervals for pediatric thyroid hormone assessment.
Abstract

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