Thyrotropin levels during hydrocortisone infusions that mimic fasting-induced cortisol elevations: a clinical research center study.
Thyrotropin levels during hydrocortisone infusions that mimic fasting-induced cortisol elevations: a clinical research center study.
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DOI：
10.1210/jcem.82.11.4376
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发表时间：
1997-11
期刊：
影响因子：
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通讯作者：
Mary H. Samuels;P. McDaniel
中科院分区：
文献类型：
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作者：
Mary H. Samuels;P. McDaniel
短期禁食和大剂量糖皮质激素治疗均能显著降低健康受试者的血清TSH水平。然而，目前尚不清楚禁食期间出现的较轻微的血清皮质醇升高是否能解释禁食诱导的TSH抑制。为了研究这个问题，8名健康受试者每人接受了3个为期2天的研究：1)基线(随机饮食)，2)禁食(总热量剥夺56小时)，3)氢化可的松(HC)的剂量和脉动模式，复制每个受试者禁食期间测量的皮质醇水平。受试者需要34-46 mg HC/24小时才能达到这些皮质醇水平。在每项研究中，在最后24小时内每隔15分钟抽取一次血样，检测血清皮质醇和促甲状腺激素水平。在每个研究结束时进行TRH刺激试验。根据设计，禁食和输注HC引起24小时血清皮质醇水平相似的轻度升高(比基线高32%)，最显著的升高出现在1400-0200小时之间。禁食使24小时平均和搏动性TSH水平比基线降低65%，而HC输注使平均和搏动性TSH水平比基线降低51%。在两项研究中，白天(0800-0200小时)TSH水平是相同的，而夜间(0200-0800小时)输注HC期间的TSH水平在基线和空腹研究之间下降。禁食或输注HC后，血清总T3和TSH对TRH的反应均有类似程度的降低。这些结果表明，内源性皮质醇水平的轻度升高可能至少在一定程度上介导了禁食诱导的TSH分泌和甲状腺激素水平的变化。此外，这些数据表明，接近生理剂量的HC以及由此导致的血清皮质醇水平在正常范围内的变化可以导致血清TSH水平的显著下降。
Both short term fasting and administration of high doses of glucocorticoids lead to marked suppression of serum TSH levels in healthy subjects. However, it is not known whether the more mild serum cortisol elevations seen during fasting can account for fasting-induced TSH suppression. To study this question, eight healthy subjects each underwent three 2-day studies: 1) baseline (adlibitum diet), 2) fasting (56 h of total caloric deprivation), 3) hydrocortisone (HC) infusions at a dose and pulsatile pattern that reproduced cortisol levels measured during each subject's fasting study. Subjects required 34-46 mg HC/24 h to achieve these cortisol levels. During each study, blood samples were drawn every 15 min during the final 24 h for serum cortisol and TSH levels. A TRH stimulation test was performed at the end of each study. By design, fasting and HC infusions induced similar mild increases in 24-h serum cortisol levels (32% over baseline), with the most significant increases seen between 1400-0200 h. Fasting decreased 24-h mean and pulsatile TSH levels 65% from baseline, whereas HC infusions decreased mean and pulsatile TSH levels 51% from baseline. Daytime (0800-0200 h) TSH levels were identical in the two studies, whereas nocturnal (0200-0800 h) TSH levels during HC infusions fell midway between baseline and fasting studies. Serum total T3 and TSH responses to TRH were decreased to a similar degree by fasting or HC infusions. These results suggest that mild elevations in endogenous cortisol levels may mediate at least in part fasting-induced changes in TSH secretion and thyroid hormone levels. In addition, these data show that near-physiological doses of HC and resulting changes in serum cortisol levels within the normal range can cause significant decreases in serum TSH levels.