de Zegher F, Vanhole C, Van den Berghe G, Devlieger H, Eggermont E, Veldhuis J D
Department of Pediatrics, University of Leuven, Belgium.
J Clin Endocrinol Metab. 1994 Aug;79(2):576-81. doi: 10.1210/jcem.79.2.8045979.
Secretory activation of the thyroid and adrenal glands is a hallmark of the neonatal adaptation to extrauterine life. TSH and cortisol play key roles in these axes. The highest serum concentrations of TSH attained over the full span of human life are normally found shortly after birth. Serum cortisol is also known to be elevated in the immediate postnatal period. However, the dynamics of TSH and cortisol secretion have hitherto not been documented on the day of birth. To study the properties of neonatal TSH and cortisol secretion, we obtained arterial blood at regular intervals (every 20 min for 6 h) from nine polycythemic newborns (gestational age, 34-41 weeks) on the first and/or fourth days after birth during a therapeutic, standardized, isovolumetric, partial exchange transfusion. One premature infant had received betamethasone antenatally. The serum TSH level of an infant with congenital hyperthyroidism of transplacental origin was also measured at the postnatal age of 1 h. Deconvolution analysis of the profiles revealed that all infants displayed a combination of basal and pulsatile TSH release. Bursts of TSH secretion occurred at a median interval of 133 min. The median serum TSH half-life was 75 min. On the day of birth, basal TSH secretion and the amplitude of pulsatile TSH secretion were higher than 3 days later. Cortisol was secreted exclusively in a pulsatile fashion. Bursts of cortisol release occurred at a median interval of 69 min. The median serum cortisol half-life was 60 min. Cortisol secretion appeared to shift gradually from a high frequency, low amplitude pattern early on the first day toward a lower frequency, higher amplitude pattern 3 days later. TSH and cortisol secretion were low in the infant who received betamethasone prenatally. Serum TSH was undetectable in the infant with congenital hyperthyroidism. In conclusion, serum TSH concentrations in the human newborn appear to be elevated on the day of birth as a result of amplified basal and pulsatile TSH release, then fall rapidly through a mechanism that decreases the amplitude of TSH secretion and are affected by modulation of the fetal thyroid axis. From the day of birth onward, cortisol was found to be released in an exclusively pulsatile mode, with characteristics that appear to depend on postnatal age and prenatal glucocorticoid exposure.
甲状腺和肾上腺的分泌激活是新生儿适应宫外生活的一个标志。促甲状腺激素（TSH）和皮质醇在这些轴系中起关键作用。在人类整个生命过程中，血清TSH浓度最高值通常在出生后不久出现。已知出生后即刻血清皮质醇也会升高。然而，TSH和皮质醇分泌的动态变化在出生当天尚未见报道。为了研究新生儿TSH和皮质醇分泌的特性，我们在治疗性、标准化、等容、部分换血输血期间，于出生后第一天和/或第四天，每隔20分钟（共6小时）从9名红细胞增多症新生儿（胎龄34 - 41周）采集动脉血。一名早产儿产前接受过倍他米松治疗。还在一名经胎盘传播的先天性甲状腺功能亢进症婴儿出生后1小时测量了其血清TSH水平。对这些曲线进行去卷积分析显示，所有婴儿的TSH释放均呈现基础分泌和脉冲式分泌相结合的方式。TSH分泌脉冲的中位间隔时间为133分钟。血清TSH的中位半衰期为75分钟。在出生当天，基础TSH分泌和脉冲式TSH分泌幅度均高于出生3天后。皮质醇仅以脉冲方式分泌。皮质醇释放脉冲的中位间隔时间为69分钟。血清皮质醇的中位半衰期为60分钟。皮质醇分泌似乎从出生第一天早期的高频、低幅度模式逐渐转变为3天后的低频、高幅度模式。产前接受倍他米松治疗的婴儿TSH和皮质醇分泌较低。先天性甲状腺功能亢进症婴儿血清TSH检测不到。总之，人类新生儿出生当天血清TSH浓度升高似乎是基础TSH分泌和脉冲式TSH分泌增强的结果，随后通过降低TSH分泌幅度的机制迅速下降，并受胎儿甲状腺轴调节的影响。从出生当天起，发现皮质醇仅以脉冲模式释放，其特征似乎取决于出生后年龄和产前糖皮质激素暴露情况。
