Mercado M, Yu V Y, Francis I, Szymonowicz W, Gold H
Department of Paediatrics, Queen Victoria Medical Centre, Melbourne, Australia.
Early Hum Dev. 1988 Mar;16(2-3):131-41. doi: 10.1016/0378-3782(88)90093-x.
Indices of thyroid function were measured in 108 infants born at 23-31 weeks gestation, after birth, at 24 and 72 h, and at 1, 3, 4, 5 and 6 weeks of age. This group was characterised by low serum thyroxine (T4), normal thyroid stimulating hormone (TSH), low-normal thyroid binding globulin (TBG), low free thyroxine index (FTI) and low triiodothyronine (T3). The incidence of hypothyroxinaemia defined as a serum T4 value of less than 65 nmol/l was 58% after birth, increasing to 84% at 1 week, after which there was progressive reduction to 36% by 6 weeks of age. Mean T4 values were inversely proportional to gestational age during this study period. Infants of 23-28 weeks gestation had significantly lower T4, TBG, FTI and T3 values compared to those of 29-31 weeks gestation. Infants who had hyaline membrane disease (HMD) had significantly lower T4 and FTI values compared to those without HMD for up to 3 weeks of age. Similar differences were found between deaths and survivors in the first week after birth. This study suggests that there is increasing delay in maturation of the hypothalamic-pituitary-thyroid axis control with increasing prematurity. In addition, the data suggest that infants who were extremely preterm or those with HMD had worse and more persistent abnormalities of thyroid function secondary to their illness and metabolic stress. The significance of our findings, in particular that of prolonged hypothyroxinaemia, is uncertain. The role of thyroid replacement therapy in these very preterm infants therefore need to be assessed with a randomised clinical trial.
对108名孕23 - 31周出生的婴儿在出生后、出生后24小时和72小时以及1、3、4、5和6周龄时测量甲状腺功能指标。该组的特点是血清甲状腺素（T4）低、促甲状腺激素（TSH）正常、甲状腺结合球蛋白（TBG）低至正常、游离甲状腺素指数（FTI）低以及三碘甲状腺原氨酸（T3）低。定义为血清T4值低于65 nmol/l的低甲状腺素血症发生率在出生后为58%，1周时增至84%，此后到6周龄时逐渐降至36%。在本研究期间，平均T4值与胎龄成反比。孕23 - 28周的婴儿与孕29 - 31周的婴儿相比，T4、TBG、FTI和T3值显著更低。患有透明膜病（HMD）的婴儿在3周龄前与未患HMD的婴儿相比，T4和FTI值显著更低。在出生后第一周死亡和存活的婴儿之间也发现了类似差异。本研究表明，随着早产程度增加，下丘脑 - 垂体 - 甲状腺轴控制的成熟延迟加剧。此外，数据表明，极早产婴儿或患有HMD的婴儿由于其疾病和代谢应激，甲状腺功能异常更严重且持续时间更长。我们研究结果的意义，尤其是长时间低甲状腺素血症的意义尚不确定。因此，需要通过随机临床试验评估甲状腺替代疗法在这些极早产婴儿中的作用。
