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Updated: Jun 29, 2025
An Ex vivo Culture System to Study Thyroid Development
Published on: June 6, 2014
Reference intervals for thyroid function from the fifth to seventh day of life in twin-pregnancy preterm neonates: an
Xin-Ting Zheng1, Xin Lin1, Mei Ma2
1Department of neonatology, College of Clinical Medicine for Obstetrics & Gynecology and Pediatrics, Fujian Maternity and Child Health Hospital, Fujian Medical University, Daoshan Road 18th, Gulou Strict, Fuzhou City, Fujian Province, 350001, China.
Insights
This study establishes the first reference intervals for thyroid function in twin neonates, aiding in diagnosing conditions like congenital hypothyroidism. Findings detail free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) levels by gestational age and sex.
Area of Science:
- Neonatal endocrinology
- Thyroid function tests
- Twin studies
Background:
- The hypothalamic-pituitary-thyroid axis matures postnatally, leading to variable thyroid hormone levels in neonates.
- Established reference intervals for thyroid function tests (free thyroxine, free triiodothyronine, thyroid stimulating hormone) are lacking for twin neonates.
- Accurate reference intervals are crucial for diagnosing thyroid dysfunction in this specific population.
Purpose of the Study:
- To establish reference intervals for thyroid function tests in twin neonates.
- To analyze variations in thyroid function based on gestational age and sex in twins.
- To provide a foundational standard for clinical assessment of thyroid health in twin infants.
Main Methods:
- Collected thyroid function data (FT4, FT3, TSH) from 273 pairs of twin neonates (2015-2022).
- Stratified neonates into 'Neonate A' (higher birth weight) and 'Neonate B' (lower birth weight) within each pair.
- Analyzed and compared reference intervals by gestational age (26-36 weeks) and sex.
Main Results:
- Established reference intervals for FT3, FT4, and TSH in twin neonates (GA 26-36 weeks).
- Significant differences in FT3 and FT4 reference intervals were observed across different gestational ages (p < 0.05).
- Male neonates showed lower FT3 and FT4 reference intervals than females in the 29-32-week gestational age group (p < 0.05).
Conclusions:
- This study presents the first reference intervals for thyroid function in twin neonates during the 5th to 7th day of life.
- These established intervals are vital for improving the diagnosis and management of congenital hypothyroidism in twins.
- The findings highlight the need for twin-specific reference ranges due to variations influenced by gestational age and sex.
Purpose:
The immature and developing hypothalamic-pituitary-thyroid axis leads to different levels of thyroid function in twin neonates, including free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) levels. No reference intervals for twins have been established until now. To compensate for this lack, we collected data and established this standard across different gestational ages (GAs) and sexes.
Methods:
A total of 273 pairs of neonates admitted to the NICU in Southeast China from 2015 to 2022 were included. Each pair was divided into Neonate A (relatively heavy birth weight (BW)) and Neonate B (relatively light BW). Their thyroid functions were analyzed to establish reference intervals and comparisons were made stratified by GA and sex.
Results:
The FT3, FT4, and TSH reference intervals in twin neonates with a GA of 26-36 weeks were as follows: Neonate A and B: 3.59 ± 0.99 and 3.57 ± 1.00 pmol/L; Neonate A and B: 17.03 ± 5.16 and 16.77 ± 5.29 pmol/L; and Neonate A and B: 4.097 ± 3.688 and 4.674 ± 4.850 mlU/L, respectively. There were significant differences between serum FT3 and FT4 reference intervals and GA (p < 0.05). The serum FT3 and FT4 reference intervals for male neonates were lower than those for female neonates in the 29-32-week group (p < 0.05).
Conclusion:
This was the first study, to our knowledge, to establish reference intervals for thyroid function in twin neonates from the fifth to seventh day of life, which will be beneficial for the diagnosis and management of congenital hypothyroidism.
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