Free thyroxine values in dried blood spots on filter paper in newborns are related to both gestational age and birth body weight (original) (raw)

Abstract

The results of free thyroxine (FT4) measurements in dried blood spots on filter paper in 744 euthyroid newborns (616 at term, 128 preterm), 10 newborns with congenital hypothyroidism and 4 euthyroid newborns with congenital TBG deficiency are reported. FT4 was measured by column adsorption chromatography of free hormone followed by radioimmunoassay in the eluate. FT4 values averaged 24 ± 0.2 pmol/L (mean ± SE) in euthyroid newborns, 23.0 ± 0.9 pmol/L in euthyroid newborns with TBG deficiency (p = NS), and 5.7 ± 0.4 pmol/L in hypothyroid newborns (p < 0.001 vs both groups). Total T4 (TT4) values in newborns with TBG deficiency were not different from those in hypothyroid newborns, but were significantly lower than those in euthyroid newborns without TBG abnormalities. FT4 values were higher in full-term newborns than in preterm newborns (25.2 ± 0.3 vs 21.2 ± 0.5 pmol/L, _p_<0.001). In both full-term and preterm newborns FT4 values in dried blood spots increased with birth body weight (bbw), virtually plateauing when bbw was greater than 2,500 g. The cut-offvalues established on the basis of the bbw (8.0 and 13.1 pmol/L forabbw of≤2,500g and > 2,500 g, respectively) showed higher specificity and predictive value of positive results than the cut-off values based on the gestational age. In any case, the sensitivity, specificity and predictive values of FT4 determinations proved to be higher than those of TT4 and TSH measurements. In conclusion: i) FT4 can be measured in dried blood spots on filter paper, advantageously replacing TT4 determination; ii) the assessment of thyroid status in newborns based on FT4 measurement must take into account the gestational age or, more reliably, the birth body weight.

Access this article

Log in via an institution

Subscribe and save

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  1. Dussault J.H., Walker P. Congenital Hypothyroidism. Marcel Dekker, New York, 1983.
    Google Scholar
  2. Robbins J., Bartalena L. Plasma transport of thyroid hormones. In: Hennemann G. (Ed.), Thyroid Hormone Metabolism. Marcel Dekker, New York, 1986, p. 3.
    Google Scholar
  3. Ekins R.P., Jackson T., Sinha A., Edwards P. Principles of free hormone measurement. J. Endocrinol. Invest. 9(Suppl. 4): 3, 1986.
    PubMed Google Scholar
  4. Pacchiarotti A., Bartalena L., Falcone M., Buratti L., Grasso L., Martino E., Pinchera A. Free thyroxine and free triiodothyronine measurement in dried blood spots on filter paper by column adsorption chromatography followed by radioimmunoassay. Horm. Metab. Res. 20: 293, 1988.
    Article CAS PubMed Google Scholar
  5. Spencer C.A. The comparative clinical value of free T4 estimation using different methodological approaches. Nuc Compact 16: 321, 1985.
    CAS Google Scholar
  6. Spencer C.A. Clinical evaluation of free T4 techniques. J. Endocrinol. Invest. 9(Suppl. 4): 57, 1986.
    PubMed Google Scholar
  7. Dubowitz L.M.S., Dubowitz V., Goldberg C. Clinical assessment of gestational age in the newborn infant. J. Pediatr. 77: 1, 1970.
    Article CAS PubMed Google Scholar
  8. Romelli P.B., Pennisi F., Vancheri L. Measurement of free thyroid hormones in serum by column adsorption chromatography and radioimmunoassay. J. Endocrinol. Invest. 2: 25, 1979.
    Article CAS PubMed Google Scholar
  9. Galen R.S., Gambino S.L. Beyond normality: the predictive value and efficiency of medical diagnoses. John Wiley & Sons, New York, 1980.
    Google Scholar
  10. Cuestas R.A. Thyroid function in healthy preterm infants. J. Pediatr. 92: 963, 1978.
    Article CAS PubMed Google Scholar
  11. Oddie T.H., Fisher D., Bernard B., Lam R.W. Thyroid function at birth in infants of 30 to 45 weeks’ gestation. J. Pediatr. 90: 803, 1977.
    Article CAS PubMed Google Scholar
  12. Wilson D.M., Hopper A.O., McDougall I.R., Bayer M.F., Hintz R.L., Stevenson D.K., Rosenfeld R.G. Serum free thyroxine in term, premature and sick infants. J. Pediatr. 101: 113, 1982.
    Article CAS PubMed Google Scholar
  13. Travert G., Lemonnier F., Fernandez Y. Free thyroxine measured in dried blood spots: results from 10,000 euthyroid and 29 hypothyroid newborns. Clin. Chem. 31: 1829, 1985.
    CAS PubMed Google Scholar
  14. Dussault J.H., Morissette J., Fiset P., Laberge E., Laberge C. Factors influencing results for thyroxine concentration in blood, as measured in paper filter spots in a screening program for neonatal hypothyroidism. Clin. Chem. 22: 1392, 1976.
    CAS PubMed Google Scholar
  15. Etling N., Padovani E., Gehin-Fouque F., Tato L. Serum and urine thyroid hormone levels in healthy preterm and small for date infants on the first and fifth day of life. Helv. Paediatr. Acta 39: 223, 1984.
    CAS PubMed Google Scholar
  16. Mizuta H., Miyai K., Ichihara K., Amino N., Harada T., Nose O., Tanizawa O. Radioimmunoassay of “free thyroxin” in dried blood spots on filter paper. Preliminary observations on the effective differentiation of subjects with congenital hypothyroidism from those with subnormal thyroxin-binding globulin and normal subjects. Clin. Chem. 28: 505, 1982.
    CAS PubMed Google Scholar
  17. Hata N., Miyai K., Ito M., Endo Y., lijimi Y., Mizuta H., Amino N., Nose O., Harada T. Enzyme immunoassay of free thyroxine in dried blood samples on filter paper. Clin. Chern. 31: 750, 1985.
    CAS Google Scholar

Download references

Author information

Authors and Affiliations

  1. Cattedra di Endocrinologia e Medicina Costituzionale, University of Pisa, Vlale del Tirreno 64, 56018, Tirrenia, PI, Italy
    A. Pacchiarotti, L. Bartalena M.D., L. Chiovato, M. Falcone, L. Buratti, M. Ciampi, L. F. Giusti, L. Grasso, G. F. Fenzi & A. Pinchera
  2. Cattedra di Endocrinologia, University of Cagliari, 09100, Cagliari, Italy
    E. Martino

Authors

  1. A. Pacchiarotti
    You can also search for this author inPubMed Google Scholar
  2. L. Bartalena M.D.
    You can also search for this author inPubMed Google Scholar
  3. L. Chiovato
    You can also search for this author inPubMed Google Scholar
  4. M. Falcone
    You can also search for this author inPubMed Google Scholar
  5. L. Buratti
    You can also search for this author inPubMed Google Scholar
  6. M. Ciampi
    You can also search for this author inPubMed Google Scholar
  7. L. F. Giusti
    You can also search for this author inPubMed Google Scholar
  8. L. Grasso
    You can also search for this author inPubMed Google Scholar
  9. G. F. Fenzi
    You can also search for this author inPubMed Google Scholar
  10. E. Martino
    You can also search for this author inPubMed Google Scholar
  11. A. Pinchera
    You can also search for this author inPubMed Google Scholar

Rights and permissions

About this article

Cite this article

Pacchiarotti, A., Bartalena, L., Chiovato, L. et al. Free thyroxine values in dried blood spots on filter paper in newborns are related to both gestational age and birth body weight.J Endocrinol Invest 11, 515–519 (1988). https://doi.org/10.1007/BF03350173

Download citation

Key-words