Hashimoto H, Sato T, Horita S, Kubo M, Ohki T
Department of Pediatrics, School of Medicine, Kanazawa University, Japan.
Endocrinol Jpn. 1991 Apr;38(2):151-7. doi: 10.1507/endocrj1954.38.151.
To clarify the maturation process of the pituitary-thyroid axis during the perinatal period, thyrotropin (TSH) response to thyrotropin releasing hormone (TRH) and serum thyroid hormone levels were examined in 26 healthy infants of 30 to 40 weeks gestation. A TRH stimulation test was performed on 10 to 20 postnatal days. Basal concentrations of serum thyroxine (T4), free thyroxine (free T4) and triiodothyronine (T3) were positively correlated to gestational age and birth weight (p less than 0.001-0.01). Seven infants of 30 to 35 gestational weeks demonstrated an exaggerated TSH response to TRH (49.7 +/- 6.7 microU/ml versus 22.1 +/- 4.8 microU/ml, p less than 0.001), which was gradually reduced with gestational age and normalized after 37 weeks gestation. A similar decrease in TSH responsiveness to TRH was also observed longitudinally in all of 5 high responders repeatedly examined. There was a negative correlation between basal or peak TSH concentrations and postconceptional age in high responders (r = -0.59 p less than 0.05, r = -0.66 p less than 0.01), whereas in the normal responders TSH response, remained at a constant level during 31 to 43 postconceptional weeks. On the other hand, there was no correlation between basal or peak TSH levels and serum thyroid hormones. These results indicate that (1) maturation of the pituitary-thyroid axis is intrinsically controlled by gestational age rather than by serum thyroid hormone levels, (2) hypersecretion of TSH in preterm infants induces a progressive increase in serum thyroid hormones, and (3) although there is individual variation in the maturation process, the feedback regulation of the pituitary-thyroid axis matures by approximately the 37th gestational week.
为阐明围产期垂体 - 甲状腺轴的成熟过程，对26名孕龄30至40周的健康婴儿进行了促甲状腺激素（TSH）对促甲状腺激素释放激素（TRH）的反应及血清甲状腺激素水平检测。在出生后10至20天进行TRH刺激试验。血清甲状腺素（T4）、游离甲状腺素（游离T4）和三碘甲状腺原氨酸（T3）的基础浓度与孕龄和出生体重呈正相关（p小于0.001 - 0.01）。7名孕龄30至35周的婴儿对TRH的TSH反应过度（49.7±6.7微单位/毫升对22.1±4.8微单位/毫升，p小于0.001），该反应随孕龄逐渐降低，孕37周后恢复正常。在反复检测的所有5名高反应者中纵向观察到对TRH的TSH反应性有类似下降。高反应者基础或峰值TSH浓度与孕龄之间呈负相关（r = -0.59，p小于0.05；r = -0.66，p小于0.01），而正常反应者在孕龄后31至43周期间TSH反应保持恒定水平。另一方面，基础或峰值TSH水平与血清甲状腺激素之间无相关性。这些结果表明：（1）垂体 - 甲状腺轴的成熟由孕龄内在控制，而非血清甲状腺激素水平；（2）早产儿TSH分泌过多导致血清甲状腺激素逐渐增加；（3）尽管成熟过程存在个体差异，但垂体 - 甲状腺轴的反馈调节在孕约37周时成熟。
