Abstract
We have reported that serum T3 in the lamb increases in the newborn period and that this increase seems to be provoked by cutting the umbilical cord (CCT). To further clarify the role of TSH in the newborn lamb we have studied serum OTSH levels and the response to exogenous TRH.
In controls serum TSH levels increased modestly to peak levels (mean 215%) at 30 min. A similar 30–45 min. peak (mean 160%) occurred in newborns in which CCT is delayed 60 min. In spite of the early OTSH A the T3 response was delayed until after CCT. The response to TRH (230 μg injected intravenously) was studied in 8 lambs. Four were under 6 hrs. of age and 4 were between 7–18 hr. Blood was sampled serially for measurements of TSH, prolactin, T4 and T3. There was a rapid rise in serum TSH and prolactin cone, in the first 15 min.: from a mean of 7.3 μU/ml and 571 ng/ml at 0 time to 14.2 μU/ml and 2130 ng/ml, respectively. A second peak was observed at 120 min. after TRH, both for TSH (24.6 μU/ml) and prolactin (2149 ng/ml), suggesting new synthesis and release. T4 and T3 levels began to rise between 60 and 120 min. Peak levels were achieved 6 hr. after TRH: T4 Δ 12.6 to 22.2 μg/100 ml and T3 δ 221 to 320 ng/100 ml.
These data indicate 1) the TSH response in the newborn lamb is much less marked than in the newborn infant 2) the TSH and T3 responses can be dissociated by CCT 3) the T3 response is not due to TSH Δ 4) the newborn lamb responds to TRH with rapid increases in TSH and prolactin.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sack, J., Fisher, D. TSH METABOLISM IN THE NEWBORN LAMB. Pediatr Res 9, 674 (1975). https://doi.org/10.1203/00006450-197508000-00056
Issue Date:
DOI: https://doi.org/10.1203/00006450-197508000-00056