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Initial and delayed thyroid-stimulating hormone elevation in extremely low-birth-weight infants
Shin Ae Yoon1, Yun Sil Chang2, So Yoon Ahn2
1Department of Pediatrics, Chungbuk National University Hospital, 1 Sunhwan-ro 776, Seowon-gu, Cheongju, 28644, South Korea.
Insights
Thyroid-stimulating hormone (TSH) elevation is common in extremely low-birth-weight infants (ELBWIs), often linked to perinatal stressors. Levothyroxine treatment reduced mortality but did not improve long-term growth or neurodevelopmental outcomes.
Area of Science:
- Neonatal endocrinology
- Pediatric critical care
- Thyroid function in preterm infants
Background:
- Thyroid-stimulating hormone (TSH) elevation is a concern in extremely low-birth-weight infants (ELBWIs).
- Understanding the incidence, causes, and outcomes of TSH elevation is crucial for this vulnerable population.
Purpose of the Study:
- To determine the incidence, etiology, and outcomes of TSH elevation in ELBWIs.
- To assess the impact of levothyroxine replacement on outcomes in ELBWIs with TSH elevation.
Main Methods:
- Retrospective analysis of newborn thyroid screening data from 584 ELBWIs (birth weight < 1000g).
- Identification of initial (≤ 2 weeks) and delayed (> 2 weeks) TSH elevations.
- Assessment of growth and neurodevelopmental outcomes at 2 years corrected age, considering levothyroxine treatment.
Main Results:
- Incidence rates of initial and delayed TSH elevations were 0.9% and 7.2%, respectively.
- Perinatal asphyxia was associated with initial TSH elevation; stressors like respiratory support and surgery were linked to delayed elevation.
- Levothyroxine treatment was associated with higher TSH, lower free T4, and reduced mortality, but no significant effect on long-term growth or neurodevelopment.
Conclusions:
- The timing of insults relative to hypothalamic-pituitary-thyroid axis maturation influences TSH elevation timing in ELBWIs.
- Levothyroxine replacement therapy in ELBWIs with TSH elevation does not appear to impact long-term growth or neurodevelopmental outcomes.
Background:
To determine the incidence, etiology, and outcomes of thyroid-stimulating hormone (TSH) elevation in extremely low-birth-weight infants (ELBWIs).
Methods:
Newborn thyroid screening data of 584 ELBWIs (birth weight, < 1000 g; gestational age, ≥ 23 weeks) were retrospectively analyzed to identify initial (≤ 2 postnatal weeks) and delayed (> 2 weeks) TSH elevations. Growth and neurodevelopmental outcomes at 2 years' corrected age (CA) were assessed according to levothyroxine replacement.
Results:
Initial and delayed TSH elevations were detected at CAs of 27 and 30 weeks, respectively, with incidence rates of 0.9 and 7.2%, respectively. All infants with initial TSH elevations had perinatal asphyxia, and 95% of those with delayed TSH elevation were exposed to various stressors, including respiratory support, drugs, and surgery within 2 weeks before diagnosis of TSH elevation. Free thyroxine (T4) levels were simultaneously reduced in 80 and 57% of infants with initial and delayed TSH elevations, respectively. Both initial and delayed TSH elevations were transient, regardless of levothyroxine replacement. Infants receiving levothyroxine replacement therapy had significantly higher TSH elevations, significantly lower free T4 levels, and significantly reduced mortality, compared to untreated infants. However, levothyroxine replacement had no significant effect on long-term growth and neurodevelopmental outcomes.
Conclusions:
The timing of insult superimposition on hypothalamic-pituitary-thyroid axis maturation is a major determinant of initial or delayed TSH elevation in ELBWIs. Levothyroxine replacement did not affect growth or neurodevelopmental outcomes in this population.
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