ABSTRACT
ABSTRACT Objective: Thyroid functions in preterm newborns may be altered in the first week of life. Hypothyroxinemia has been commonly reported in these babies, which could be due to the immaturity of the hypothalamic pituitary thyroid axis or acute illness. It could have a long-term impact on the developing brain of these babies. We conducted this study to estimate the incidence of transient hypothyroxinemia of prematurity (THOP) and to determine its risk factors. Materials and methods: We analyzed thyroid stimulating hormone (TSH) and free T4 levels of 64 preterm neonates admitted in the neonatal intensive care unit. TSH and free T4 levels were measured in the first week and then at 14-21 days of life to estimate the incidence of THOP and determine its risk factors. We also estimated the incidence of congenital hypothyroidism (CH) and delayed TSH elevation in CH. Risk analysis was conducted using simple and multiple logistic regression, and numerical data was compared using the Mann Whitney U test and t test. Results: THOP was seen in 25% of the preterm babies. Caesarean delivery, presence of one or more morbidities, mechanical ventilation, birth weight ≥ 1,500 g, and gestational age ≥ 32 weeks were identified as risk factors for THOP based on simple logistic regression. In multiple regression, mechanical ventilation and gestational age ≥ 32 weeks were significantly associated with THOP. CH was seen in 2 (3.1%) babies, and 1 of these cases had delayed TSH elevation. Conclusion: Thyroid abnormalities are common in preterm admitted neonates. Mechanical ventilation is an independent risk factor for development of THOP.
Subject(s)
Humans , Female , Pregnancy , Infant, Newborn , Infant , Intensive Care Units, Neonatal , Congenital Hypothyroidism , Thyroxine , Infant, Premature , Thyrotropin , Risk FactorsABSTRACT
Objective: To perform neurodevelopmental evaluation at 18 to 24 months’ corrected age in very low birth infants (VLBW) with transient hypothyroxinemia. Design: Cohort study. Setting: Maternity teaching hospital. Patients: Premature infants who were previously evaluated for thyroid hormone values in the first weeks of life were included. Intervention: Data of these infants who weighed ≤1500 g and ≤32 weeks of gestation were retrieved for the current study. Available subjects (n=56) were evaluated for neurodevelopmental status at 18 to 24 months of corrected age. Bayley Scales of Infant Development –Second Edition (BSID-II) was performed to define Mental developmental index (MDI) and Psychomotor developmental index (PDI). Results: The mean MDI and PDI scores were similar between the infants with and without transient hypothyroxinemia of prematurity (THOP) [79.9 ± 14.9 vs 70 ± 20.7, respectively (P=0.54); and 92.2 ± 16.4 vs 85.6 ± 18.9, respectively (P=0.68)]. After adjustment for gestational age and multiple prenatal, perinatal, and early and late neonatal variables, THOP was not associated with an increased risk of disabling cerebral palsy, or a reduction of MDI and PDI scores. Conclusions: THOP may not be an important cause of problems in neurologic and mental development detected at the age of 18 to 24 months’ corrected age.
ABSTRACT
The morbidity of transient hypothyroxinemia of prematurity (THOP) was high. There is controversial about thyroid hormone supplementation in THOP. Clinical studies suggest that thyroid hormone supplementation can reduce the incidence of patent ductus arteriosus,but no effect on the mortality and the incidence of respiratory disease.Thyroid hormone supplementation can improve the neurodevelopmental outcomes in infants with gestational age less than 28 weeks with THOP, but no effect on infants with gestational age more than 28 weeks. Future research should focus on the normal range of thyroid hormone according to gestational age in preterm infants,and randomized clinical trial welldesigned stratified according to gestational age to study the long-term neurodevelopmental outcome of thyroid hormone replacement therapy in infants with THOP