Thyroid Function Test in Pre-term Neonates During the First Five Weeks of Life

Area of Science:

• Neonatology
• Endocrinology
• Pediatric Research

Background:

• Congenital hypothyroidism (CHT) is a common endocrine disorder in newborns, affecting approximately 1 in 3,000 live births.
• Prevalence, causes, and associated conditions of abnormal newborn thyroid screening tests vary across populations.
• This study investigated CHT in preterm infants and factors influencing thyroid function.

Purpose of the Study:

• To assess the prevalence of CHT in preterm newborns (gestational age < 35 weeks).
• To identify demographic factors and conditions, such as respiratory distress syndrome (RDS), that influence thyroid function in this population.
• To evaluate the necessity of repeated thyroid function tests in preterm infants.

Main Methods:

• Studied 100 preterm newborns with gestational age less than 35 weeks.
• Measured serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels within the first 5 days and again within the first 5 weeks of life.
• Analyzed the impact of gestational age and RDS on thyroid function test alterations.

Main Results:

• The mean gestational age was 32.35 ± 1.97 weeks.
• CHT was diagnosed in 13% of the preterm infants studied.
• Gestational age significantly affected FT4 levels during follow-up (P < 0.001), while TSH levels were not significantly influenced (P = 0.062). Adjusted TSH and FT4 levels differed significantly between infants with and without CHT during follow-up (P = 0.006 and P = 0.000, respectively).

Conclusions:

• Thyroid function tests require repetition in preterm infants, particularly those with lower gestational ages, to accurately diagnose CHT.
• CHT should be considered in newborns diagnosed with respiratory distress syndrome (RDS).
• Gestational age is a critical factor in monitoring thyroid function in preterm neonates.