Thyroid function and dysfunction in preterm infants-Challenges in evaluation, diagnosis and therapy

Area of Science:

• Neonatalogy
• Endocrinology
• Developmental Neuroscience

Background:

• Thyroid hormones are essential for brain development from gestation through infancy.
• Preterm infants, especially those with low birth weight, are at higher risk for thyroid dysfunction due to immature hypothalamic-pituitary thyroid axis.
• Factors like postnatal illness, medications, and iodine status can influence thyroid function tests in neonates.

Purpose of the Study:

• To review thyroid physiology in preterm infants.
• To discuss the impact of gestational age and neonatal conditions on thyroid function tests.
• To explore optimal screening strategies and predictors for differentiating transient from permanent thyroid dysfunction.

Main Methods:

• Literature review of thyroid physiology and dysfunction in preterm neonates.
• Analysis of factors affecting thyroid function tests in premature infants.
• Discussion of current guidelines and controversies in screening and treatment.

Main Results:

• Hypothyroxinaemia of prematurity, often with delayed TSH elevation, is common in low birth weight preterm infants.
• Transient hypothyroxinaemia is typical, but permanent hypothyroidism can occur due to thyroid dysgenesis or enzyme defects.
• The neurodevelopmental impact of untreated thyroid dysfunction in premature infants remains largely unknown.

Conclusions:

• Careful monitoring and long-term follow-up of thyroid function are crucial for preterm infants.
• Differentiating transient from permanent hypothyroidism requires understanding various influencing factors.
• Optimal timing for screening and treatment of thyroid dysfunction in premature infants requires further investigation.