title: Thyroid dysfunction in very low birth weight preterm infants.
abstract: OBJECTIVE
  Thyroid dysfunction is common in preterm infants. Congenital hypothyroidism causes neurodevelopmental impairment, which is preventable if properly treated. This study was conducted to describe the characteristics of thyroid dysfunction in very low birth weight infants (VLBWIs), evaluate risk factors of hypothyroidism, and suggest the reassessment of thyroid function with an initially normal thyroid-stimulating hormone (TSH) as part of a newborn screening test.
  
  
  METHODS
  VLBWIs (January 2010 to December 2012) were divided into two groups according to dysfunction-specific thyroid hormone replacement therapy, and associated factors were evaluated.
  
  
  RESULTS
  Of VLBWIs, 246 survivors were enrolled. Only 12.2% (30/246) of enrolled subjects exhibited thyroid dysfunction requiring thyroid hormone replacement. Moreover, only one out of 30 subjects who required thyroid hormone treatment had abnormal thyroid function in the newborn screening test with measured TSH. Most of the subjects in the treatment group (22/30) exhibited delayed TSH elevation. Gestational age, Apgar score, antenatal steroids therapy, respiratory distress syndrome, patent ductus arteriosus, sepsis, intraventricular hemorrhage, postnatal steroids therapy, and duration of mechanical ventilation did not differ between the two groups. Birth weight was smaller and infants with small for gestational age were more frequent in the treatment group.
  
  
  CONCLUSIONS
  Physicians should not rule out suggested hypothyroidism, even when thyroid function of a newborn screening test is normal. We suggest retesting TSH and free thyroxine in high risk preterm infants with an initially normal TSH level using a newborn screening test.
authors.affiliation: Department of Pediatrics, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Pediatrics, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Ga Won
authors.initials: GW
authors.lastname: Jeon
authors.affiliation: Department of Pediatrics, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Jong Beom
authors.initials: JB
authors.lastname: Sin
keywords: Congenital hypothyroidism; Neonatal screening; Premature infant; Thyroid function tests; Very low birth weight infant