Thyroid Disorders in Preterm Infants: Prevalence, Etiologies, and Thyroid Function Test Characteristics

Pichaya Vathanasakpuban; Buranee  Yangthara; Nithiwat Vatanavicharn; Somporn Liammongkolkul; Ornsuda Lertbannaphong

doi:10.33192/smj.v78i9.281716

Authors

Pichaya Vathanasakpuban Division of Endocrinology and Metabolism, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
Buranee Yangthara Division of Neonatology, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
Nithiwat Vatanavicharn Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
Somporn Liammongkolkul Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
Ornsuda Lertbannaphong Division of Endocrinology and Metabolism, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand

DOI:

https://doi.org/10.33192/smj.v78i9.281716

Keywords:

congenital hypothyroidism, hyperthyrotropinemia, hypothyroxinemia, maternal preeclampsia, preterm infants, thyroid disorders

Abstract

Background: Thyroid hormone is essential for preterm infant development, particularly neurological. Understanding thyroid disorder prevalence and function test characteristics enables proper interpretation and risk identification.

Objectives: To determine the prevalence, etiologies, risk factors, and thyroid function test characteristics of thyroid disorders in preterm infants.

Materials and Methods: This retrospective review included infants with gestational age (GA) < 37 weeks born at Siriraj Hospital in 2022. Infants with genetic syndromes, multiple congenital anomalies, chromosomal abnormalities, or maternal thyroid disease were excluded. Thyroid-stimulating hormone (TSH) from neonatal dried blood spots and thyroid function tests from blood were obtained at 1 week, 2 weeks, and from 4 weeks until term-corrected age. Multiple logistic regression identified risk factors.

Results: Among 603 infants, thyroid disorder prevalence was 2.99% (18/603). Disorders included hyperthyrotropinemia 8/18, hypothyroxinemia 4/18, congenital hypothyroidism 2/18, transiently elevated free thyroxine 2/18, central hypothyroidism 1/18, and transiently low TSH 1/18. Maternal preeclampsia was statistically significantly associated with hyperthyrotropinemia (P = 0.039; adjusted odds ratio 5.064; 95% CI 1.084–23.661). TSH increased from the first to second week in infants with GA 28–33 weeks, particularly GA 31–33 weeks, but decreased in GA 34–36 weeks. Free thyroxine increased with GA in infants < 34 weeks but decreased in GA 34–36 weeks.

Conclusions: Thyroid disorder prevalence was approximately 3%, with hyperthyrotropinemia most common. Maternal preeclampsia was a hyperthyrotropinemia risk factor. TSH and free thyroxine levels trended upward in infants with GA < 34 weeks but downward in GA > 34 weeks.

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