Thyroid function in healthy normal, low birthweight and preterm infants

Abstract

To delineate more precisely the role of gestational age, weight at birth and thyroid status at birth on the postnatal changes in thyroid hormone levels, serum T4, T3, TSH and in some cases FT3I were measured at birth and at 3-4 h, 24-30 h, 6-9 days and 13-20 days. Subjects studied were healthy appropriate-for-date (AFD) and small-for-date (SFD) term neonates and healthy AFD and SFD preterm children. At birth T4 and T3 are related to both gestational age and weight with T4 and T3 showing lower values in preterm and SFD term neonates than in AFD term children. After birth T4 and T3 concentrations show a better correlation with gestational age than with weight at birth. For TSH no correlation was found at birth, a positive correlation at 24-30 h, no correlation at 6-9 days and a negative correlation at 13-20 days both with gestational age and weight at birth. In term and close-to-term infants (36 weeks) individual T4 levels at 6-7 days show a close relationship with those at birth; in the younger children (34 and 35 weeks) lower T4 values are found, despite equal cord blood values. The individual cord blood FT3I/TSH values correlate well with those at 6-7 days of age. It is concluded that after birth all children have changing T4 and T3 values, but the pattern and level are influenced by the maturity of the child and its thyroid status at birth measured by T4 and by the FT3I/TSH ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid-stimulating immunoglobulins and thyroid function tests in two siblings with neonatal thyrotoxicosis

“…The cause of the bronze pigmentation is uncertain. It may be due to products of bilirubin-sensitized photodegradation of copper porphyrins [3] and could then occur only when plasma bilirubin, copper, and porphyrins are increased simultaneously (as in cholestasis), -perhaps accounting for the rarity of the syndrome. The bronze discolouration seems to be harmless, and the well-being of the infant reflects the underlying disease condition [5].…”

Thyroid Stimulating Hormone and Thyroxine Screening in the Preterm Newborn: Reference Values

“…Abbiamo così stabilito, in una popolazione sufficientemente ampia, i livelli di TSH e tT4 appropriati per le varie età gestazionali. In precedenza vari studi sono stati effettuati nel feto e nel neonato a termine e pretermine, per valutare l'influenza dell'età gestazionale sulla funzionalità tiroidea, sia prelevando il sangue fetale con funicolocentesi [23][24][25] o alla nascita con il prelievo di sangue cordonale [26][27][28].…”

“…Alcuni studi hanno analizzato i livelli di TSH e tT4 alla nascita nel sangue cordonale [26][27][28].…”

“…Bongers-Shokking e coll. [27] nel 1984 hanno esaminato i livelli di TSH e tT4 in varie epoche: alla nascita su sangue cordonale in 107 nati, a 24-30 h in 25 nati, a 6-9 giorni in 104 nati e a 13-20 giorni di vita in 57 neonati. Il tT4 mostrava una correlazione positiva con l'EG e con il peso sia alla nascita che nei periodi successivi; al contrario tali AA.…”

“…In the present study we examined a total population of 1,671 adapted for gestational age newborns (AGA) of which 1,159 resulted in full term and 512 resulted in preterm. The population was divided into eight groups of [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] and for each age group the median values of TSH and tT4 was determined. The TSH and tT4 were obtained in the 2nd -3rd day of life at the screening for Congenital Hypothyroidism.…”