Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Original Article
  • Published:

Reference Ranges for Thyroid Function Tests in Premature Infants Beyond the First Week of Life

Journal of Perinatology volume 21, pages 531–536 (2001)Cite this article

Abstract

OBJECTIVES:To establish reference ranges for the more sensitive assays of thyrotropin and the best available assays of free thyroxine in premature infants after the first week of life.

STUDY DESIGN:Free thyroxine measurements by direct equilibrium dialysis and thyrotropin measurements by third generation immunometric assay were measured in 120 healthy premature infants 25 to 36 weeks' gestation at birth and every 3 weeks until hospital discharge. Infants were stratified by postconceptional age. Differences in free thyroxine and thyrotropin levels among groups were determined by ANOVA. Correlations between hormone measurements and gestational and postnatal ages were sought by linear regression analysis. Reference ranges were determined as arithmetic (free thyroxine) and geometric (thyrotropin) mean±2 SD ranges.

RESULTS:From 120 infants, 164 samples were obtained and grouped by postconceptional age at sampling. Free thyroxine was not different among postconceptional age groups and did not correlate with gestational or postnatal age. The free thyroxine reference range based on these data was 10 to 33 pmol/l (0.8 to 2.6 ng/dl). Thyrotropin did not correlate with gestational age. There was a clinically trivial but statistically significant (r2=0.03, p<0.05) correlation of thyrotropin with postnatal age. The thyrotropin reference based on these data was 0.8 to 12 mU/l.

CONCLUSIONS:Free thyroxine was closely regulated in these premature infants and levels were similar to those in older children and adults, once the natal surge in thyrotropin has subsided. After the first week of life a single range for each hormone appeared appropriate for all premature infants until 40 weeks postconceptional age.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Similar content being viewed by others

References

  1. Jacobsen BB, Peitersen B, Anderson HJ, Hummer L Serum concentrations of thyroxine-binding globulin, prealbumin and albumin in healthy fullterm, small-for-gestational age and preterm newborn infants Acta Paediatr Scand 1979 68 49–55

    Article  CAS  Google Scholar 

  2. Hirano T, Singh J, Srinivasan G, Pildes R Post-natal thyroid function in low birth weight infants; a longitudinal assessment of free thyroxine and thyroid hormone binding globulin Acta Endocrinol 1985 110 56–60

    Article  CAS  Google Scholar 

  3. Fisher DA Euthyroid low thyroxine (T4) and triiodothyronine (T3) states in prematures and sick infants Pediatr Clin North Am 1990 37 1297–312

    Article  CAS  Google Scholar 

  4. Redding RA, Pereira C Thyroid function in respiratory distress syndrome (RDS) of the newborn Pediatrics 1974 54 423–8

    CAS  PubMed  Google Scholar 

  5. Klein AH, Stinson D, Foley B, Larsen PR, Foley TP Thyroid function studies in preterm infants recovering from the respiratory distress syndrome J Pediatr 1977 91 261–3

    Article  CAS  Google Scholar 

  6. Cuestas RA, Engel RR Thyroid function in preterm infants with respiratory distress syndrome J Pediatr 1979 94 643–6

    Article  CAS  Google Scholar 

  7. Wilson DM, Hopper AO, McDougal IR, et al Serum free thyroxine values in term, premature, and sick infants J Pediatr 1982 101 113–7

    Article  CAS  Google Scholar 

  8. Franklin RC, Purdie GL, O'Grady CM Neonatal thyroid function: prematurity, prenatal steroids, and respiratory distress syndrome Arch Dis Child 1986 61 589–92

    Article  CAS  Google Scholar 

  9. Stahnke N, Stenzel E, Hellwege H Thyroid function in prematures with respiratory distress syndrome Acta Endocrinol Suppl 1986 279 354–60

    Article  CAS  Google Scholar 

  10. Nelson JC, Tomei RT Direct determination of free thyroxin in undiluted serum by equilibrium dialysis/radioimmunoassay Clin Chem 1988 34 1737–44

    CAS  PubMed  Google Scholar 

  11. Kaptein EM Clinical application of free thyroxine determinations In: Klee GE, editor. Clinics in Laboratory Medicine vol. 13 1993 p. 653–72

  12. Spencer CA Clinical utility and cost-effectiveness of sensitive thyrotropin assays in ambulatory and hospitalized patients Mayo Clin Proc 1988 63 1214–22

    Article  CAS  Google Scholar 

  13. Nicoloff JT, Spencer CA Clinical review 12: the use and misuse of the sensitive thyrotropin assays J Clin Endocrinol Metab 1990 71 553–8

    Article  CAS  Google Scholar 

  14. Nelson JC, Wilcox RB Further studies on thyroxin-binding globulin-dependence in equilibrium dialysis assays of free thyroxin Clin Chem 1991 37 128–9

    CAS  PubMed  Google Scholar 

  15. Nelson JC, Wilcox RB, Pandian MR Dependence of free thyroxine estimates obtained with equilibrium tracer dialysis on the concentration of thyroxine-binding globulin Clin Chem 1992 38 1294–300

    CAS  PubMed  Google Scholar 

  16. Nelson JC, Weiss RM, Wilcox RB Underestimates of serum free T4 concentrations by free T4 immunoassays J Clin Endocrinol Metab 1994 79 76–9

    CAS  PubMed  Google Scholar 

  17. Wang R, Nelson JC, Weiss RM, Wilcox RB Accuracy of free thyroxine measurements across natural ranges of thyroxine binding to serum proteins Thyroid 2000 10 31–9

    Article  CAS  Google Scholar 

  18. Nelson JC, Clark SJ, Borut dl, Tomei RT, Carlton EI Age-related change in serum free thyroxine during childhood and adolescence J Pediatr 1993 123 899–905

    Article  CAS  Google Scholar 

  19. Adams LM, Emery JR, Clark SJ, Carlton EI, Nelson JC Reference ranges for newer thyroid function tests in premature infants J Pediatr 1995 126 122–7

    Article  CAS  Google Scholar 

  20. Babson SG Growth of low-birth-weight infants J Pediatr 1970 77 11–8

    Article  CAS  Google Scholar 

  21. Babson SG, Benda GI Growth graphs for the clinical assessment of infants of varying gestational age J Pediatr 1976 89 814–20

    Article  CAS  Google Scholar 

  22. Ballard JL, Khoury JC, Wedig K, Wang L, Eilers-Walsman BL, Lipp R New Ballard score, expanded to include extremely premature infants J Pediatr 1991 119 417–23

    Article  CAS  Google Scholar 

  23. Odell WD, Griffin J, Zahradnik R Two-monoclonal-antibody sandwich-type assay for thyrotropin, with use of avidin–biotin separation technique Clin Chem 1986 32 1873–8

    CAS  PubMed  Google Scholar 

  24. Conover WJ Practical Nonparametric Statistics. 2nd ed Wiley 1980

    Google Scholar 

  25. Grubbs FE, Green B Extension of sample sizes and percentage points for significance tests of outlying observations Technometrics 1972 14 847–54

    Article  Google Scholar 

  26. Klein RZ, Carlton EL, Faix JD, et al Thyroid function in very low birth weight infants Clin Endocrinol 1997 47 411–7

    Article  CAS  Google Scholar 

  27. van Wassenaer AG, Kok JH, Dekker FW, de Vulder JJM Thyroid function in very preterm infants: influences of gestational age and disease Pediatr Res 1997 42 604–9

    Article  CAS  Google Scholar 

  28. Rooman RP, Du Caju MVL, Op De Beeck L, Van Reempts P, Van Acker KJ Low thyroxinaemia occurs in the majority of very preterm newborns Eur J Pediatr 1996 155 211–5

    Article  CAS  Google Scholar 

  29. Kodama S, Mori Y, Miyoshi M, et al Thyroid function in premature infants Kobe J Med Sci 1992 38 109–16

    CAS  PubMed  Google Scholar 

  30. Hirano T, Singh J, Srinivasan G, Pildes R Postnatal thyroid function in low birth weight infants: a cross-sectional assessment of free thyroxine and thyroid hormone binding globulin Eur J Pediatr 1982 139 244–6

    Article  CAS  Google Scholar 

  31. Fuse Y, Shimizu M, Uga N, Fujii T, Irie M Maturation of feedback control of thyrotropin in premature infants J Dev Physiol 1990 14 17–22

    CAS  PubMed  Google Scholar 

  32. Mantagos S, Koulouris A, Makri M, Vagenakis AG Development of thyrotopin circadian rhythm in infancy J Clin Endocrinol Metab 1992 74 71–4

    CAS  PubMed  Google Scholar 

  33. Fisher DA, Nelson JC, Carlton EI, Wilcox RB Maturation of human hypothalamic–pituitary–thyroid function and control Thyroid 2000 10 229–34

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank Dr. Grenith Zimmerman for helpful review and criticism of the manuscript. We also thank the medical students, David Huang and Suzanne Clark, who assisted us in computer data entry and chart review for this study.

Author information

Authors and Affiliations

  1. Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, CA, USA

    Susan J Clark MD, Douglas D Deming MD, Janet R Emery MD & Linda M Adams MD

  2. Quest Diagnostics, Inc, San Juan Capistrano, CA, USA

    Esther I Carlton MT & Jerald C Nelson MD

  3. Departments of Medicine and Pathology, Loma Linda University School of Medicine, Loma Linda, CA, USA

    Jerald C Nelson MD

Authors
  1. Susan J Clark MD
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Douglas D Deming MD
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Janet R Emery MD
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Linda M Adams MD
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Esther I Carlton MT
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jerald C Nelson MD
    View author publications

    You can also search for this author in PubMed Google Scholar

Additional information

There was no extramural funding for this study.

3626 NE 46th St., Suite 30C, Seattle, WA, 98105, USA

Utah Valley Regional Medical Center, 1034 North 500 West, Provo, UT, 84604, USA

Rights and permissions

Reprints and permissions

About this article

Cite this article

Clark, S., Deming, D., Emery, J. et al. Reference Ranges for Thyroid Function Tests in Premature Infants Beyond the First Week of Life. J Perinatol 21, 531–536 (2001). https://doi.org/10.1038/sj.jp.7210572

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/sj.jp.7210572

This article is cited by

Search

Advanced search

Quick links