Establishment Of Reference Range For Free Thyroxine Hormone (FT4) In Neonates: A Cross Sectional Study

Abstract

Introduction: Reference intervals play a crucial role in clinical laboratory test interpretation and patient care. Accurate reference intervals for free thyroxine (FT4) in neonates are crucial for diagnosing and managing thyroid-related conditions but are currently lacking due to neonatal-specific physiological variations. This study aims to establish precise FT4 reference ranges to improve neonatal thyroid function assessment and clinical care.

Aim: To establish a reference range for free thyroxine hormone (FT4) in neonates

Materials and Methods: This cross-sectional study was conducted at the Obstetrics and Gynecology (OBG) and Neonatal Intensive Care Unit (NICU) of Father Muller Medical College and Hospital, Mangalore from January 2019 to December 2019. A total of 240 healthy term neonates (37-42 weeks of gestation) with no congenital anomalies, infections, or significant perinatal complications were included in the study. Serum free thyroxine (FT4) levels were measured using the Roche Cobas e601 electrochemiluminescence method. Blood samples were collected from neonates within the first week of life. Data analysis was performed following Clinical and Laboratory Standards Institute (CLSI) guidelines. Medians, 2.5th, and 95th percentiles for FT4 were calculated to determine the reference range. Demographic parameters such as gestational age, birth weight, and sex of the neonates were recorded.

Results: The established reference range for FT4 in neonates was found to be 1.4-4.1 ng/dl. There was no significant difference between genders (p- value= 0.987), with male neonates having a range of 1.4-4.2 ng/dl and female neonates having a range of 1.4-3.68 ng/dl.

Conclusion: This study highlights the importance of establishing accurate reference intervals for clinical decision-making. The reference range for FT4 in neonates differs from that in adults, emphasizing the need for age-specific reference interval. Further studies with larger sample sizes are warranted to validate and refine gender-specific reference intervals for FT4 in neonates.