Serum tri-iodothyronine, thyroxine, and thyrotrophin concentrations in newborns during the first 2 days of life (original) (raw)
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Journal of Clinical Investigation, 1973
Low triiodothyronine (T3) and high normal thyroxine (T4) concentrations are present in cord sera from full term infants. To examine this phenomenon further, radioimmunoassay of T3 and T4 was carried out in paired maternal and cord sera as well as capillary sera from neonates at different intervals after delivery. Free T3 and free T4 concentrations were also estimated in cord and maternal sera by equilibrium dialysis. In 12 paired specimens, the T3 concentration in cord sera was significantly lower than the maternal level (51±4 vs. 161±11 ng/100 ml, mean +SE). Mean free T3 concentration was also lower in the cord samples (0.15±0.02 vs. 0.31+0.04 ng/100 ml), whereas total and free T4 concentrations were not significantly different. Umbilical vein and artery samples from 11 neonates did not differ significantly in their T3 and T4 concentrations. In seven infants the mean T3 concentration increased from 51±3 ng/100 ml at delivery to 79±13 at 15 min and 191±16 at 90 min. In four other infants the mean T3 concentration at 24 and 48 h was ,not significantly different from the 90 min value of the previous group. Less pronounced changes were observed for T4 which increased from 12.3±2.0 Ag/100 ml (mean +SE) at delivery to 14.1±1.9 at 90 min and appeared to have reached a plateau at approximately twice the cord value by 24-48 h after delivery.
European Journal of Endocrinology, 1998
Objective: To investigate the effect on thyroid hormone metabolism of the administration of thyroxine to very preterm infants. Design and methods: Two hundred infants of less than 30 weeks gestation were enrolled into a randomized, double-blind, placebo-controlled trial. Thyroxine (T 4 ) (at a fixed daily dose of 8 mg/kg birthweight) or placebo was started 12-24 h after birth and discontinued 6 weeks later. Plasma concentrations of T 4 , tri-idothyronine (T 3 ), reverse T 3 (rT 3 ), TSH, and thyroxine-binding globulin were measured weekly during trial medication and 2 weeks thereafter. Results: The T 4 and the placebo group each comprised 100 infants. Antenatal, perinatal, and postnatal clinical characteristics were comparable in both groups. T 4 and rT 3 were significantly increased in the T 4 group. TSH concentrations were depressed in the T 4 group and T 3 was significantly decreased, probably as a result of TSH depression. The T 4 /T 3 and T 4 /rT 3 ratios differed significantly between the two study groups. Conclusions: Daily T 4 administration during the first 6 weeks after birth to infants of less than 30 weeks gestation prevents hypothyroxinemia, but decreases plasma T 3 concentrations. Our finding possibly implies that very preterm infants should receive supplements of both T 4 and T 3 .
European Journal of Endocrinology, 1993
Objective: To investigate the effect on thyroid hormone metabolism of the administration of thyroxine to very preterm infants. Design and methods: Two hundred infants of less than 30 weeks gestation were enrolled into a randomized, double-blind, placebo-controlled trial. Thyroxine (T 4 ) (at a fixed daily dose of 8 mg/kg birthweight) or placebo was started 12-24 h after birth and discontinued 6 weeks later. Plasma concentrations of T 4 , tri-idothyronine (T 3 ), reverse T 3 (rT 3 ), TSH, and thyroxine-binding globulin were measured weekly during trial medication and 2 weeks thereafter. Results: The T 4 and the placebo group each comprised 100 infants. Antenatal, perinatal, and postnatal clinical characteristics were comparable in both groups. T 4 and rT 3 were significantly increased in the T 4 group. TSH concentrations were depressed in the T 4 group and T 3 was significantly decreased, probably as a result of TSH depression. The T 4 /T 3 and T 4 /rT 3 ratios differed significantly between the two study groups. Conclusions: Daily T 4 administration during the first 6 weeks after birth to infants of less than 30 weeks gestation prevents hypothyroxinemia, but decreases plasma T 3 concentrations. Our finding possibly implies that very preterm infants should receive supplements of both T 4 and T 3 .
The Netherlands Journal of Medicine
Objective: To investigate the effect on thyroid hormone metabolism of the administration of thyroxine to very preterm infants. Design and methods: Two hundred infants of less than 30 weeks gestation were enrolled into a randomized, double-blind, placebo-controlled trial. Thyroxine (T 4 ) (at a fixed daily dose of 8 mg/kg birthweight) or placebo was started 12-24 h after birth and discontinued 6 weeks later. Plasma concentrations of T 4 , tri-idothyronine (T 3 ), reverse T 3 (rT 3 ), TSH, and thyroxine-binding globulin were measured weekly during trial medication and 2 weeks thereafter. Results: The T 4 and the placebo group each comprised 100 infants. Antenatal, perinatal, and postnatal clinical characteristics were comparable in both groups. T 4 and rT 3 were significantly increased in the T 4 group. TSH concentrations were depressed in the T 4 group and T 3 was significantly decreased, probably as a result of TSH depression. The T 4 /T 3 and T 4 /rT 3 ratios differed significantly between the two study groups. Conclusions: Daily T 4 administration during the first 6 weeks after birth to infants of less than 30 weeks gestation prevents hypothyroxinemia, but decreases plasma T 3 concentrations. Our finding possibly implies that very preterm infants should receive supplements of both T 4 and T 3 .
Thyroid Function in the Neonate
Clinical Endocrinology, 1973
Urinary thyroxine and triiodothyronine levels, when corrected for creatinine excretions, were significantly elevated in 5-day-old infants as compared with levels in normal adults and women during the third trimester of pregnancy. This was consistent with the finding that their free thyroxine index was increased and suggests that the circulating levels of free thyroid hormones are raised in early infancy. Circulating levels of thyroid-stimulating hormone were not significantly different at 6 days as compared with adult values. I N T R O D U C T I O N Early work on thyroid function in the neonatal period suggested that serum protein bound iodine (PBI) levels were raised during the first days of life (Danowski et al., 1951 ; Man et al., 1952), and it seemed that this was due, at least partly, to an increase in the thyroid hormone binding capacity (TBC) of serum proteins (Spafford et al., 1960; Marks et al., 1961 ; Fisher & Oddie, 1964). This increase in TBC probably results from the increased levels of oestrogen found in both the mother and fetus. It is unlikely, however, that this is sufficient to account for all the changes in neonatal thyroid function, since the circulating levels of both free thyroxine (T4) (Marks et al., 1966) and free triiodothyronine (T3) (Erenberg et al., 1973) are elevated in early life, whereas they remain normal in pregnant women (Fang & Selenkow, 1970) and in mothers at term (Fisher et al., 1969). Furthermore, neonates have an increased thyroidal I3'I uptake and clearance (Fisher et al., 1962). Fisher & Ode11 (1969) suggested that the increased thyroid activity was secondary to the acute release of thyrotrophin (TSH), possibly in response to extrauterine cooling and/or stress; this surge of TSH is maximal at about 30 min, followed by a rapid return towards normal by 48 hr. The present study reports urinary thyroid hormone levels and the results of other in vitro thyroid function tests in a group of 5-day-old infants.
Sao Paulo Medical Journal, 2000
CONTEXT: Screening programs not only offer the opportunity to trace and treat almost all cases of congenital hypothyroidism but also mean large savings to the health system. However, carefully planned strategies are necessary to extend their benefits and reduce costs. OBJECTIVE: To determine the possible influence of maternal diseases that affect maternal-fetal placenta dynamics on primary thyroid stimulating hormone (TSH) screening for congenital hypothyroidism. DESIGN: Prospective non-randomized clinical trial with at least 3 months of follow-up. SETTING: A public university referral center [CAISM/Hospital das Clínicas, Faculty of Medicine, University of Campinas, Campinas, SP]. PARTICIPANTS: 415 neonates divided into 5 groups: eighty-three infants born from cardiac mothers; 98 from mothers that had toxemia; 54 of the mothers had diabetes mellitus; 40 were HIV positive and 140 had no diseases. INTERVENTION: All newborns had cord blood samples collected on filter paper at birth. MA...
Influence of Perinatal Factors and Sampling Methods on TSH and Thyroid Hormone Levels in Cord Blood
Endocrinologia Japonica, 1991
To evaluate the effect of perinatal factors and sampling methods on thyroid stimulating hormone (TSH) and thyroid hormone levels in cord blood, serum TSH, free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in 124 healthy term neonates. Eighty-eight infants were born in normal vaginal deliveries, 25 were delivered by vacuum extractor and 11 by Cesarean section. There was no significant difference among the three infant groups in the mean TSH levels. Birth weight, the infant's sex, duration of labor and uterotonic agents had no effect on cord serum TSH and free thyroid hormone levels in the neonates born by normal vaginal delivery. To assess the adequacy of specimen collection, mixed cord blood samples, obtained by a direct application of cord on a filter paper, and venous blood withdrawn with a plastic syringe were collected in another 200 infants. There was a significant linear correlation in the TSH concentration in mixed cord blood and cord venous serum from the same individuals, while a poor correlation was found in T4 values from two specimens. Our results suggest that the TSH value in cord blood is less influenced by perinatal factors, including the sampling method, and the mixed cord blood collected by this technique might be a feasible alternative specimen for a TSH screening program with cord blood which is useful in countries where neonatal blood is not available.
Journal of Evidence Based Medicine and Healthcare, 2015
Congenital hypothyroidism is a more common pediatric endocrine disorder and also most common preventable cause of mental retardation. Early diagnosis by measuring Thyroid hormones thyroxine (T4), Thyroid Stimulating Hormone (TSH) levels and prompt treatment is crucial in improving intellectual outcome and for growth of the baby. There are several perinatal factors which influence cord blood TSH, T4 values which has to be considered while interpreting the results. Umbilical cord blood samples were collected for assessment of TSH and T4 in 100 newborns. The influence of birth weight and gestational age on T4 & TSH levels was assessed. On comparing mean TSH and T4 levels among preterm and term infants, it was found that there was statistically significant difference in the mean TSH levels between term and preterm infants. Difference in mean T4 levels among low birth weight and normal birth weight infants was statistically significant. To conclude Birth weight & gestational age have influence on Cord blood TSH and T4 levels and a caution in their interpretation should be considered.