Small for gestational age is a risk factor for the development of delayed thyrotropin elevation in infants weighing less than 2000 g

Atsushi Uchiyama, Hirokazu Watanabe, Hidehiko Nakanishi, Satsuki Totsu

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Objective: Delayed thyrotropin (TSH) elevation (dTSHe) is common in low birthweight infants. We aimed to clarify the risk factors for the development of dTSHe in infants weighing <2000 g at birth. Patients and Methods: According to Japanese guidelines, infants with birthweight <2000 g underwent second capillary TSH screening within 30 days, either at 1 month of age; or when weight reached 2.5 kg; or at discharge. dTSHe was defined as TSH >20 mIU/L by venous sampling following a normal result (<15 mIU/L) at first screening aged 4-6 days. For each infant who developed dTHSe three babies without dTSHe were selected and matched for gestational age and birth year. Small for gestational age (SGA) was defined as a birthweight <10th percentile for the gestational age and sex. A multivariate analysis was performed to identify risk factors for the development of dTSHe. Results: Among the 911 study infants, 17 infants (1.9%) had dTSHe. The median (range) birthweight in the dTSHe group (796 [388-1912] g) was significantly smaller than the comparison group (961 [408-1981] g) (P = 0.04). The number (%) of SGA infants was significantly higher in the dTSHe group (12 [71%]) than in the comparison group (13 [25%]) (P = 0.001). The multivariate analysis revealed that SGA was an independent risk factor for the development of dTSHe (adjusted odds ratio, 9.0; 95% confidence interval, 2.5-32.8; P = 0.001). Conclusions: Small for gestational age is an independent risk factor for the development of dTSHe in infants with a birthweight <2000 g. The influence of prematurity, a matching criterion for this study, on dTSHe requires additional study.

Original languageEnglish
Pages (from-to)431-436
Number of pages6
JournalClinical Endocrinology
Volume89
Issue number4
DOIs
Publication statusPublished - Oct 2018
Externally publishedYes

Keywords

  • congenital hypothyroidism
  • delayed thyrotropin elevation
  • levothyroxine
  • low birthweight infants
  • neonatal intensive care unit
  • newborn thyroid screening
  • small for gestational age

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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