Does Hypothyroxinemia of Preterm Neonates Persist Beyond 7 weeks of Life?

Sharma, Jhulan Das; Nazir, Marriam; Khan, Abdul Gofur; Hoque, Baharul

doi:10.1007/s12098-019-02935-2

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…In an observational study, fT4 level normalized by 7 weeks of birth in preterm neonates. [17] An Indian study also had observed that hypothyroxinemia of prematurity is transient and spontaneous recovery occurs by 6-8 weeks of age, which supports observations made in the present study. [18] The current study also observed that preterm neonates mature and stabilize to have normal thyroid function by 2-4 weeks of age.…”

Section: Discussionsupporting

confidence: 92%

A study on normalization of hypothyroxinemia in neonates below 34 weeks of gestation

Gaonkar

Shenoi

Sathyanarayana³

et al. 2022

JPED

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Objectives: The aim of the study was to estimate the time required for normalization of hypothyroxinemia of prematurity in neonates below 34 weeks of gestation. Material and Methods: A retrospective study was conducted in neonates born below 34 weeks of gestation, between January 2015 and December 2016. Data were collected on free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels, tested on days 3, 14, 28, and 42. Gestational age, birth weight, use of antenatal steroids, mechanical ventilation, and various preterm morbidities, along with development at 18 months of corrected age, were comparatively analyzed in neonates with and without hypothyroxinemia. The median time for normalization of fT4 in all these variables was estimated. Results: On day 3, low fT4 was noted in 69 (37.7%) out of 183 neonates born below 34 weeks of gestation; all had normal TSH levels. Hypothyroxinemia showed statistically significant association with gestational age, birth weight, antenatal steroid use, respiratory distress syndrome, invasive ventilation, shock, sepsis, patent ductus arteriosus (PDA), anemia during stay in neonatal intensive care unit, and development at 18 months. Median time for normalization was 14 days in most of the neonates, and 28 days in those with <28 weeks of gestational age, weight of <1000 g and with shock, anemia, and PDA. Two infants with hypothyroxinemia received therapy with levothyroxine at 6 weeks for a short duration, as TSH was high. Conclusion: Hypothyroxinemia of prematurity takes 14–28 days to normalize based on maturity, weight, and illnesses. This study recommends serum fT4 testing at 2 weeks of life, provided congenital hypothyroidism was ruled out by 3–4 days of life, using direct blood spot card metabolic screening.

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Section: Discussionsupporting

confidence: 92%

A study on normalization of hypothyroxinemia in neonates below 34 weeks of gestation

Gaonkar

Shenoi

Sathyanarayana³

et al. 2022

JPED

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“…The accompanying article in this issue of IJP therefore, is a timely opportunity to review these concepts [1]. There are multiple causes for the apparent low T4 (with normal TSH) in preterm neonates.…”

mentioning

confidence: 99%

“…The as-yet immature fetal thyroid abruptly becomes the only source of T4 after birth. The more preterm the baby is, the lower is the T4, as highlighted by Sharma et al [1]. Hepatic production of thyroxine binding globulin (TBG) is suboptimal.…”

mentioning

confidence: 99%

Hypothyroxinemia in Preterm Neonates: Not Always Hypothyroidism

Bhatia

2019

Indian J Pediatr

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“…Few studies [ 15 , 16 , 17 , 18 ] have evaluated the course of tT4 beyond four weeks of life in preterm infants, most of them [ 16 , 17 , 18 ] have included a relatively small sample and have measured tT4 concentration on serum and not in DBS. These studies [ 15 , 16 , 17 , 18 ] reported that in preterm infants below 30 weeks, tT4 concentration declines in the first weeks of life and returns to normal concentration between four and eight weeks of life, which is consistent with our results.…”

Section: Discussionmentioning

confidence: 99%

Reference Percentiles and Changes over Time for Total Thyroxine in Preterm Infants: A Retrospective Cohort Study

et al. 2020

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Hypothyroxinemia of prematurity increases the rate of false-positive results in total thyroxine (tT4)-based screening programs for congenital hypothyroidism. The use of specific cutoff values for preterm infants has been proposed, but data on tT4 reference ranges in this population are limited. The primary aim was to establish reference percentiles for tT4 in dried blood spots among Mexican preterm infants. Secondary aims included a comparison of the change of tT4 concentrations over time according to gestational age and to discuss its impact on tT4-based screening programs. This was a retrospective cohort study; 1561 preterm infants were included. Percentile 10th for tT4 concentration at 24–27, 28–30, 31–34, and 35–36 weeks of gestational age, measured in the first week of life was: 47.6, 56.6, 82.3, and 117.1 nmol/L, respectively. tT4 concentrations were compared in three different time points: first week of life, 2–3 weeks of life, and term-corrected gestational age (38 weeks of gestation), progressively increased in infants below 30 weeks, remained stable in infants from 31 to 34 weeks, and decreased in late preterm newborns (35–36 weeks). This study suggests that preterm infants may require the use of lower tT4 cutoff values in newborn screening.

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Does Hypothyroxinemia of Preterm Neonates Persist Beyond 7 weeks of Life?

Cited by 4 publications

References 22 publications

A study on normalization of hypothyroxinemia in neonates below 34 weeks of gestation

A study on normalization of hypothyroxinemia in neonates below 34 weeks of gestation

Hypothyroxinemia in Preterm Neonates: Not Always Hypothyroidism

Reference Percentiles and Changes over Time for Total Thyroxine in Preterm Infants: A Retrospective Cohort Study

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