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Postnatal thyroid hormones for preterm infants with transient hypothyroxinaemia

  • Review
  • Intervention

Authors


Abstract

Background

Extremely premature infants are at risk of transient hypothyroxinaemia in the first weeks after birth. These low thyroid hormone levels are associated with an increased incidence of neonatal morbidity, mortality and longer term developmental impairments. Thyroid hormone therapy might prevent these problems.

Objectives

To determine the evidence for thyroid hormone therapy in preterm infants with transient hypothyroxinaemia (low thyroid hormone level, normal TSH) for improvement of neonatal outcomes and neurodevelopment.

Search methods

Searches were performed of The Cochrane Central Register of Controlled (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966 - March 2006), PREMEDLINE (March 2006), EMBASE (1980 - March 2006), previous reviews including cross references, abstracts and conference proceedings, supplemented by requests to expert informants.

Selection criteria

Trials enrolling preterm infants with transient hypothyroxinaemia (low thyroid hormone level, normal TSH level) in the neonatal period, using random or quasi-random patient allocation to thyroid hormone therapy compared to control (placebo or no treatment).

Data collection and analysis

Independent assessment of trial quality and data extraction by each review author. Synthesis of data using relative risk (RR) and weighted mean difference (WMD) using standard methods of the Cochrane Collaboration and its Neonatal Review Group.

Main results

Only one study was eligible. Chowdhry (1984) enrolled 23 infants < 1250 g and 25 - 28 weeks gestation with transient hypothyroxinaemia (serum total T4 ≤ 4 μg/dl and TSH ≤ 20 IU/L). Infants were randomised to thyroxine 10 μg/kg/day or placebo beginning on day 15 and continuing daily for seven weeks. Chowdhry (1984) reported no neonatal mortality and one infant death in each group prior to discharge. No significant difference was reported in CLD at 28 days or 36 weeks, patent ductus arteriosus, necrotising enterocolitis, retinopathy or prematurity, weight gain, growth in head circumference or length. No significant difference was reported for mean T4 levels between thyroxine and placebo treated infants on day 21, 35, 49, 63 and 77 after birth. Free T4 was not measured. Neurodevelopmental follow up was inadequate to draw any conclusions from.

Authors' conclusions

There is insufficient evidence to determine whether use of thyroid hormones for treatment of preterm infants with transient hypothyroxinaemia results in changes in neonatal morbidity and mortality, or reductions in neurodevelopmental impairments. Further research is required.

摘要

背景

早產兒暫時性低甲狀腺素血症之甲狀腺素補充

極度早產兒在出生後第一週內可能會有暫時性的低甲狀腺素血症,並可能因而導致新生兒的併發症,死亡率,及較長期的發育異常。甲狀腺素補充可能能夠避免這些問題。

目標

針對早產兒暫時性低甲狀腺素血症(血中甲狀腺素偏低,但TSH值正常)情形,投與甲狀腺素是否能改善其預後。

搜尋策略

作者收集了包括The Cochrane Central Register of Controlled (CENTRAL, The Cochrane Library, Issue 1, 2006), MEDLINE (1966  March 2006), PREMEDLINE (March 2006), EMBASE (1980  March 2006) 等資料庫,以及包括交叉分析、摘要、及討論紀錄的回顧性評論,並且包括專家的資料補充。

選擇標準

選擇標準為在新生兒時期有暫時性低甲狀腺素血症 (血中甲狀腺素偏低,但TSH值正常)之早產兒,使用隨機或準隨機分類至甲狀腺素治療組或使用安慰劑的對照組。

資料收集與分析

每一位作者均獨立地評估試驗品質及數據摘錄。相對危險性(RR)及加權平均數(WMD)之統計則採用考科藍共同研究計劃及其新生兒回顧評論群之標準方法。

主要結論

只有一篇chowdhry (1984)的研究合乎標準。該研究包含了23位小於1250克重且妊娠期介於25 – 28週間的新生兒,他們都有暫時性低甲狀腺素血症(血中濃度T4小於4 ug/dl,TSH小於20 IU/L)。這些新生兒被隨機分配成兩組,其中一組每天服用 thyroxine 10 μg/kg/day,另一組則從第15週開始每天服用安慰劑直到7週大。兩組對象在出院前均無死亡案例,且其在第28天或第36週大時,包括開放性動脈導管、壞死性腸炎、視網膜病變、體重頭圍身長的成長等各方面均無顯著差異。血液中的平均T4濃度在出生後第21、35、49、63及77天大時均無顯著差異,游離T4濃度則未進行測量。神經發展部份則尚無足夠數據可提供結論。

作者結論

沒有足夠的證據可以證明關於暫時性低甲狀腺素血症之早產兒投與甲狀腺素能改變死亡率或罹病率或神經發展,此情形尚待進一步研究。

翻譯人

本摘要由高雄醫學大學附設醫院陳利旻翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

針對隨機試驗所做的系統性評論並無法證明對暫時性低甲狀腺素血症之早產兒投與甲狀腺素能改善其預後。極度早產兒在出生後第一週內常有暫時性的低甲狀腺素血症,並可能因而導致新生兒的併發症、死亡率、及較長期的發育異常。甲狀腺素補充可能能夠避免這些問題。一項小型研究針對這些新生兒進行了投予甲狀腺素或安慰劑的隨機試驗,發現投予甲狀腺素之新生兒並無明顯益處。然而這篇研究並未提供足夠的證據以決定甲狀腺素治療是否有效,尚有待進一步研究。

Plain language summary

Postnatal thyroid hormones for preterm infants with transient hypothyroxinaemia

A systematic overview of randomised trials does not provide sufficient evidence to determine whether thyroid hormone treatment of preterm infants with transiently low thyroid hormone levels results in changes in neonatal outcomes or reductions in developmental impairments. Extremely premature infants frequently have transiently low thyroid hormone levels in the first weeks after birth. These low thyroid hormone levels are associated with an increased incidence of complications and death in the newborn period and longer term developmental impairments. Thyroid hormone therapy might prevent these problems. One small trial comparing thyroid hormone treatment to no treatment of infants with transiently low thyroid hormone levels reported no benefit from treatment of these infants. However, this is insufficient evidence to determine if thyroid hormone treatment is effective. Further research is needed.