Dare Gustavo Leopoldo Rodrigues, de Castro Margaret, Maciel Lea Maria Zanini
Division of Endocrinology, Department of Internal Medicine, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil.
Thyroid. 2008 Apr;18(4):401-9. doi: 10.1089/thy.2007.0237.
To reevaluate the responses of thyrotropin-releasing hormone (TRH) stimulation test in baseline condition as well as after the administration of graded supraphysiological doses of liothyronine (L-T(3)) in normal subjects.
To assess various parameters related to the hypothalamic-pituitary axis and peripheral tissue responses to L-T(3) in 22 normal individuals (median age: 30.5 years). Subjects were submitted to an intravenous TRH test at baseline condition and also to the oral administration of sequential and graded doses of L-T(3) (50, 100, and 200 microg/day), each given over 3 days, at an outpatient clinic. Blood samples were obtained for thyrotropin (TSH) and prolactin (PRL) at basal and then 15, 30, and 60 minutes after the TRH injection. Effects of L-T(3) administration on cholesterol, creatine kinase, retinol, ferritin, and sex hormone-binding globulin (SHBG) were also measured at basal and after the oral administration of L-T(3).
TRH administration resulted in an increase of 4- to 14-fold rise in serum TSH (8.3 +/- 2.5-fold), and in a slight rise in serum PRL concentrations (3.8 +/- 1.5-fold). Administration of graded doses of triiodothyronine (T(3)) resulted in a dose-dependent suppression of TSH and PRL. Basal thyroxine-binding globulin (TBG) and cholesterol levels decreased, and ferritin and SHBG increased after L-T(3) administration, while creatine kinase and retinol did not change throughout the study. There was a positive correlation between basal TSH and TSH peak response to TRH at basal condition and after each sequential L-T(3) doses. On the other hand, TSH peak response to the TRH test did not predict cholesterol, TBG, ferritin, or SHBG values.
Using the current methods on hormone and biochemical analysis, we standardized the response of many parameters to TRH stimulation test after sequential and graded T(3) suppression test in normal subjects. Our data suggest that the evaluation of the responses of the hypothalamus-pituitary axis to TRH test as well as the impact of L-T(3) on peripheral tissues were not modified by the current methods.
重新评估正常受试者在基础状态下以及给予不同剂量超生理剂量的碘塞罗宁（L-T3）后促甲状腺激素释放激素（TRH）刺激试验的反应。
评估22名正常个体（中位年龄：30.5岁）下丘脑-垂体轴及外周组织对L-T3反应的各项参数。受试者在基础状态下接受静脉TRH试验，并在门诊接受连续递增剂量的L-T3（50、100和200微克/天）口服给药，每次给药持续3天。在基础状态下以及TRH注射后15、30和60分钟采集血样检测促甲状腺激素（TSH）和催乳素（PRL）。在基础状态下以及口服L-T3后还检测L-T3给药对胆固醇、肌酸激酶、视黄醇、铁蛋白和性激素结合球蛋白（SHBG）的影响。
给予TRH后血清TSH升高4至14倍（8.3±2.5倍），血清PRL浓度略有升高（3.8±1.5倍）。给予递增剂量的三碘甲状腺原氨酸（T3）导致TSH和PRL呈剂量依赖性抑制。基础状态下甲状腺素结合球蛋白（TBG）和胆固醇水平降低，L-T3给药后铁蛋白和SHBG升高，而肌酸激酶和视黄醇在整个研究过程中未发生变化。基础状态下及每次连续给予L-T3剂量后，基础TSH与TRH刺激试验的TSH峰值反应之间呈正相关。另一方面，TRH试验的TSH峰值反应不能预测胆固醇、TBG、铁蛋白或SHBG值。
采用当前的激素和生化分析方法，我们在正常受试者中进行连续递增T3抑制试验后，对TRH刺激试验中许多参数的反应进行了标准化。我们的数据表明，当前方法未改变下丘脑-垂体轴对TRH试验反应以及L-T3对外周组织影响的评估。
