Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Department of Clinical Epidemiology, Hyogo College of Medicine, Nishinomiya, Japan.
Clin Endocrinol (Oxf). 2020 Nov;93(5):605-612. doi: 10.1111/cen.14260. Epub 2020 Jun 21.
We evaluated the response to the thyrotropin-releasing hormone (TRH) stimulation test in very low-birth weight (VLBW) infants to elucidate the aetiology of transient hypothyroxinaemia of prematurity (THOP).
We performed TRH stimulation tests on 43 VLBW infants. Subjects were divided into two groups; a THOP group (N = 11; basal TSH < 15 mU/L and basal FT4 ≤ 0.8 ng/dL) and a non-THOP group (N = 32; basal TSH < 15 mU/L and basal FT4 > 0.8 ng/dL). Basal FT4 and FT3 were measured before, and TSH (0, 30, 60, 90, 120 and 180 minutes) was measured after, the administration of TRH (7 µg/kg). We calculated the ratio of TSH 180 minutes to THS 0 minute as the primary outcome. We also collected data on T3 and rT3 in this study.
In both groups, TSH 30 minutes values were the highest. However, the ratios of TSH 180 minutes to THS 0 minutes in the non-THOP group and the THOP group were (median [IQR]) 1.3 [1.0-1.7] and 3.0 [1.5-5.3] (P < .01). No significant differences were observed in T3 (1.0 [0.8-1.3] and 0.7 [0.4-0.7] ng/mL, P = .06). However, in the THOP group, rT3 was significantly lower than that of the non-THOP group (168.0 [148.1-197.0] and 92.9 [74.7-101.6] pg/mL, P < .01).
The delayed decrease in the TSH concentration after the peak for the TRH tests and decreased levels of rT3 suggest that the main aetiology for THOP is suppression at the level of the hypothalamus, but not inactivation of peripheral thyroid hormone metabolism.
我们评估了极低出生体重（VLBW）婴儿对促甲状腺激素释放激素（TRH）刺激试验的反应，以阐明早产儿短暂性甲状腺功能减退症（THOP）的病因。
我们对 43 名 VLBW 婴儿进行了 TRH 刺激试验。受试者分为两组；THOP 组（N=11；基础 TSH<15 mU/L 和基础 FT4≤0.8 ng/dL）和非 THOP 组（N=32；基础 TSH<15 mU/L 和基础 FT4>0.8 ng/dL）。在给予 TRH（7 µg/kg）之前测量基础 FT4 和 FT3，在给予 TRH 之后测量 TSH（0、30、60、90、120 和 180 分钟）。我们将 TSH 180 分钟与 TSH 0 分钟的比值作为主要结果进行计算。在这项研究中，我们还收集了 T3 和 rT3 的数据。
在两组中，TSH 30 分钟的值最高。然而，非 THOP 组和 THOP 组 TSH 180 分钟与 TSH 0 分钟的比值分别为（中位数[IQR]）1.3[1.0-1.7]和 3.0[1.5-5.3]（P<.01）。T3 无显著差异（1.0[0.8-1.3]和 0.7[0.4-0.7]ng/mL，P=0.06）。然而，在 THOP 组中，rT3 明显低于非 THOP 组（168.0[148.1-197.0]和 92.9[74.7-101.6]pg/mL，P<.01）。
TRH 试验后 TSH 浓度峰值后下降延迟，rT3 水平降低提示 THOP 的主要病因是下丘脑水平的抑制，而不是外周甲状腺激素代谢的失活。
