"Unveiling thyroid dysfunction in preterm neonates": A prospective observational study

Area of Science:

• Neonatal Medicine
• Endocrinology
• Pediatrics

Background:

• Thyroid dysfunction is prevalent in preterm neonates due to immature hypothalamic-pituitary-thyroid axis, increased metabolic demands, and drug exposure.
• Transient thyroid dysfunctions may resolve spontaneously, necessitating careful monitoring rather than immediate treatment.
• Current guidelines advocate for repeated screening in preterm infants to accurately assess thyroid status.

Purpose of the Study:

• To determine the incidence of thyroid dysfunction requiring thyroxine replacement therapy in preterm neonates (≤32 weeks) up to 40 weeks of corrected gestational age.
• To identify independent predictors associated with thyroid dysfunction requiring treatment in this vulnerable population.

Main Methods:

• A prospective observational study involving 421 preterm neonates (≤32 weeks) admitted to a NICU in South India.
• Serial screening of serum free thyroxine (FT4) and thyroid stimulating hormone (TSH) at 72 hours, 2 weeks, and 3-4 weeks postnatal age.
• Management decisions based on abnormal screening results.

Main Results:

• Among 376 neonates completing all screenings, 4% (95% CI 2.2-6.5%) required thyroxine replacement therapy.
• Persistent hypothyroxinemia (2.65%) was the most common diagnosis, followed by congenital hypothyroidism with delayed TSH elevation (1.06%) and primary congenital hypothyroidism (0.26%).
• Extremely low birth weight (ELBW) and necrotizing enterocolitis (NEC) ≥ stage 2 were significant independent predictors for thyroid dysfunction requiring treatment.

Conclusions:

• The incidence of treatable thyroid dysfunction in preterm neonates is higher than in the general population.
• Repeated screening, particularly up to 3-4 weeks postnatal age, is essential to avoid overtreatment and detect late-onset thyroid dysfunction.
• Identifying high-risk factors like ELBW and NEC can aid in targeted monitoring of preterm infants for thyroid abnormalities.