[Thyroid hormone Levels in very preterm neonates and extremely preterm]

Area of Science:

• Neonatalogy
• Endocrinology
• Pediatrics

Background:

• Preterm infant thyroid function is affected by immature regulatory axes, disease, and medications.
• Establishing normal free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels in preterm infants is challenging.
• This study addresses the controversy surrounding normal FT4 levels in this population.

Purpose of the Study:

• To determine the distribution of FT4 and TSH values in preterm infants.
• To analyze these values at 15 days of chronological age.
• To investigate variations based on gestational age categories.

Main Methods:

• A cross-sectional study analyzed data from 308 newborns.
• Infants were categorized into gestational age groups: 31-34, 28-30, and 23-27 weeks.
• Statistical analysis included Pearson Chi-square, T-Test, and ANOVA.

Main Results:

• Significant differences in average FT4 levels were found across gestational age ranges (p=0.000).
• FT4 levels were 1.13 ng/dl (31-34 wks), 1.03 ng/dl (28-30 wks), and 0.92 ng/dl (23-27 wks).
• No significant differences in TSH levels were observed across gestational age categories (p=0.663).

Conclusions:

• Established FT4 and TSH level distributions for very preterm and extremely preterm infants in the studied population.
• Findings indicate differences compared to previously published data.
• Highlights the need for population-specific reference ranges for FT4 in preterm infants.