Thyroid hormone and thyrotropin responses to parturition in premature infants with and without the respiratory distress syndrome
Klein, A.H.; Foley, B.; Kenny, F.M.; Fisher, D.A.
Pediatrics 63(3): 380-385
1979
ISSN/ISBN: 0031-4005 PMID: 108662 Document Number: 148100
Serum thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), thyrotropin (TSH) and thyroxine-binding globulin (TBG) concentrations were measured in well full-term infants (group 1), well premature infants (group 2) and premature infants with the respiratory distress syndrome (group 3). Samples were collected at birth and at 2, 12 and 24 h after delivery. Significant increases in mean serum TSH concentrations occurred in all 3 groups 2 h after delivery, but the 2 h levels measured in groups 2 and 3 were less than those in group 1 infants. Serum T4 concentrations increased significantly after delivery in groups 1 and 2 but not in group 3 newborns. Mean TBG concentrations did not vary significantly in any of the groups. Serum T3 concentrations increased significantly at 2 h in all 3 groups but were significantly depressed at 12 and 24 h in group 3 infants. Mean serum rT3 concentrations decreased after birth in group 2 and 3 in contrast to group 1 newborns. The mean value increased significantly between 2-24 h in group 3 infants. The pattern of decreasing serum T3 and increasing rT3 concentrations in group 3 infants between 2-24 h resembled the pattern of change in triiodothyronines in ill adult patients, which suggested that these variations were due primarily to illness and not to prematurity.