Associations between Early Thyroid-Stimulating Hormone Levels and Morbidities in Extremely Preterm Neonates

Area of Science:

• Neonatal Medicine
• Endocrinology
• Pediatric Neurology

Background:

• High-end cutoffs for thyroid-stimulating hormone (TSH) are established for hypothyroidism therapy in extremely preterm infants.
• The clinical significance of low TSH levels in this population remains largely unknown.
• This study investigated the relationship between TSH levels and neonatal morbidities.

Purpose of the Study:

• To determine if the spectrum of TSH levels at newborn screening correlates with specific morbidities in extremely preterm neonates.
• To analyze the association between different TSH level categories and neonatal outcomes.

Main Methods:

• A multicenter cohort study analyzed 434 extremely preterm neonates.
• Neonates were screened for TSH levels within 24-96 hours of birth and categorized into four groups based on TSH values.
• Neonatal morbidities were assessed using the modified Neonatal Therapeutic Intervention Scoring System.

Main Results:

• Groups with lower TSH levels showed significant differences in gestational age, birth weight, and postnatal age at sampling.
• Lower TSH groups had higher incidences of mechanical ventilation, hypoxic respiratory failure, intraventricular hemorrhage, and periventricular leukomalacia.
• Specifically, the lowest TSH group (<0.5 µU/mL) exhibited significantly higher severity scores for respiratory distress syndrome and brain injury compared to the next TSH group, even after adjusting for confounding factors.

Conclusions:

• Low TSH levels in extremely preterm neonates are associated with increased severity of respiratory distress syndrome and brain injuries.
• Further research with larger cohorts and comprehensive thyroid function data is required to elucidate the interactions within the hypothalamic-pituitary-thyroid axis in this population.