Higher Incidence Rates of Hypothyroidism and Late TSH Rise in Preterm Very-Low-Birth-Weight Infants at a Tertiary Care Center

Abstract

Background/Aims: Preterm newborns with a very low birth weight (VLBW) of < 1,500 g have an atypical form of hypothyroidism with a delayed rise in TSH, necessitating a second newborn screening specimen collection. The aims of this study were to survey the compliance with second newborn screening to detect delayed TSH rise in VLBW preterm infants at a tertiary care center, and to determine the rate of atypical hypothyroidism. Methods: Retrospective review of the records of 104 preterm VLBW infants. Late TSH rise was defined as an increase in TSH concentration after 14 days of age in the presence of a normal initial screen. Results: The compliance rate was 92% for the second screening. High rates of hypothyroidism (16.3%) and of late TSH rise (4.8%) were detected. Patients with hypothyroidism had a significantly lower birth weight (p = 0.01) and longer hospital stay (p = 0.004). Patients with late versus those with early TSH rise had a significantly lower mean birth weight (851 ± 302 vs. 1,191 ± 121 g, p = 0.004). Conclusion: The rates of early and late TSH rise in this VLBW population were higher than those in the literature and could be due to the use of povidone-iodine disinfectants. The yield of a second TSH screening in this study was high indicating the need for vigilance in screening VLBW preterm infants.

Is It Necessary to Measure T4 In Screening of Congenital Hypothyroidism in Preterm Infants?

“…Considering that 7(1.5%) in first one and1 (0.49%) in the second one, the level of TSH was more than20ng/dl, the probability of permanent hypothyroidism in our patients was low. In the research by Tfayli H, the rate of higher TSH level in preterm babies was significant and the researchers concluded that this result could be due to the use of povidone-iodine disinfectants in very low birth weight infants [18].…”

Guideline for the treatment of hypothyroidism in prematurity

“…[ 1 ] The frequency of congenital hypothyroidism is high in preterm and low-birth-weight (LBW) newborns compared to normal ones due to insufficient development of the hypothalamic-pituitary axis (1/400 vs 1/4000). [ 8 9 ]…”