Ghose R R, Upadhyay H P
Postgrad Med J. 1986 Jan;62(723):11-4. doi: 10.1136/pgmj.62.723.11.
Prospective measurements of serum thyrotrophin and thyroxine concentrations were made in six patients with primary hypothyroidism treated consecutively with an incremental regimen of oral thyroxine. A fall in thyrotrophin occurred over several months, accompanied by a concurrent slow rise in serum thyroxine. Those patients with the highest initial values for thyrotrophin showed the typical curvilinear decline in thyrotrophin, whereas the remaining patients disclosed a transient rise in thyrotrophin for the first 3 months. This paradoxical rise was not associated with depression of cardiac output or glomerular filtration rate. The significance of thyrotrophin augmentation is uncertain, but it may be more common than generally appreciated. It did not occur in those patients with the most severe degrees of thyroid deficiency. Thyroxine exerts a dual action, and augmentation of thyrotrophin may reflect a dominant effect of increased protein synthesis, in contrast to negative feedback inhibition which suppresses thyrotrophin. These opposing actions are in competition at different dose levels of thyroxine, and may contribute not only to augmentation or suppression of thyrotrophin, but also to the curvi-linear pattern of fall. Such variations impair the utility of thyrotrophin as an index of euthyroidism.
对6例原发性甲状腺功能减退患者采用递增剂量口服甲状腺素连续治疗，并对其血清促甲状腺激素和甲状腺素浓度进行前瞻性测量。促甲状腺激素在几个月内下降，同时血清甲状腺素缓慢上升。促甲状腺激素初始值最高的患者，促甲状腺激素呈典型的曲线下降，而其余患者在最初3个月促甲状腺激素出现短暂上升。这种矛盾的上升与心输出量或肾小球滤过率降低无关。促甲状腺激素升高的意义尚不确定，但可能比普遍认为的更为常见。在甲状腺功能严重减退的患者中未出现这种情况。甲状腺素具有双重作用，与抑制促甲状腺激素的负反馈抑制相反，促甲状腺激素升高可能反映了蛋白质合成增加的主导作用。这些相反的作用在甲状腺素的不同剂量水平上相互竞争，不仅可能导致促甲状腺激素的升高或抑制，还可能导致其呈曲线下降模式。这种变化损害了促甲状腺激素作为甲状腺功能正常指标的效用。
