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Thyroid function in very-low-birth-weight infants with intraventricular hemorrhage
D A Paul1, K H Leef, J L Stefano
1Department of Pediatrics, Christiana Care Health Services, Newark, DE, USA.
Insights
Intraventricular hemorrhage (IVH) in premature infants may initially affect thyroid function, but this association diminishes by 2-4 weeks. Transient hypothyroxinemia remains common in preterm infants during this period.
Area of Science:
- Neonatology
- Endocrinology
- Pediatric Neurology
Background:
- Premature infants are at risk for thyroid dysfunction.
- Intraventricular hemorrhage (IVH) is a common complication in preterm neonates.
- Thyroid function monitoring is crucial in high-risk infant populations.
Purpose of the Study:
- To investigate the natural course of thyroid function in infants with intraventricular hemorrhage (IVH).
- To compare thyroid hormone levels in infants with and without IVH.
- To identify factors associated with thyroid dysfunction in preterm infants.
Main Methods:
- A cohort of 247 infants weighing <1,500 grams was analyzed.
- Total T4 and thyrotropin levels were measured during the first week (Test 1) and at 2-4 weeks postnatal age (Test 2).
- Multivariate analysis was used to assess the association between IVH and thyroid function, controlling for other factors.
Main Results:
- Infants with IVH showed an increased odds of low T4 (< or = 6 microg/dL) on Test 1 (OR 2.8).
- By Test 2 (2-4 weeks), IVH was not independently associated with low T4.
- Fifty-nine percent of infants exhibited transient hypothyroxinemia at Test 2.
- Gestational age remained associated with extremely low T4 (< or = 4 microg/dL) at Test 2.
Conclusions:
- Transient hypothyroxinemia is prevalent in preterm infants at 2-4 weeks of age.
- While IVH may be associated with transient low T4 in the first week, it is not an independent predictor of low T4 at 2-4 weeks.
- Gestational age is a significant factor associated with extremely low T4 in later infancy.
Abstract:
The objective of this investigation was to study the natural course of thyroid function in infants with intraventricular hemorrhage (IVH). A cohort of infants < 1,500 grams birth weight, n=247, were included in the analysis. Total T4 and thyrotropin from newborn screening during the 1st week of life (Test 1) and from repeat screening at 2-4 weeks postnatal age (Test 2) were compared in infants with IVH (n=43) and a group of infants without IVH. Fifty-nine percent of infants still had transient hypothyroxinemia at the time of Test 2. After multivariate analysis, infants with IVH had an increased odds of having a T4 < or = 6 microg/dL on Test 1 (OR 2.8, 95% CI 1.2-6.5), but at the time of Test 2 IVH was not associated with an increased odds of having a low T4. Only gestational age (OR 1.6, 95% CI 1.1-2.5) remained associated with an increased odds of having an extremely low T4 (< or = 4 microg/dL) at this time. Transient hypothyroxinemia remains common at 2-4 weeks of age in preterm infants. IVH is not independently associated with having a low T4 at this time.