Kleinmann R E, Vagenakis A G, Braverman L E
J Clin Endocrinol Metab. 1980 Aug;51(2):399-403. doi: 10.1210/jcem-51-2-399.
Oral cholecystographic agents induce a decrease in serum T3 and an increase in serum T4 and rT3 concentrations in normal subjects. However, their effect on TSH secretion in man is unclear. In the present study, the serum TSH concentration was increased above baseline values 5 days after the administration of 3 g iopanoic acid (IA) in five of six euthyroid volunteers (an increase of borderline significance), and the TSH response to TRH was significantly augmented after IA administration. In four other euthyroid subjects who had received IA 3 days earlier, the administration of T3 (5 microgram, five times daily) for the next 2 days restored the serum T3 concentration toward baseline values and prevented the IA-induced increase in TRH-stimulated serum TSH concentrations. It is concluded from the present study that IA enhances pituitary thyrotroph sensitivity to TRH and that this effect may be related, at least in part, to the IA-induced decrease in circulating T3 as well as the previously demonstrated inhibitory effect of IA on the pituitary conversion of T4 to T3. This decrease in the serum T3 concentration after IA administration is due primarily to inhibition of peripheral 5-monodeiodination of T4 and, possibly, to a direct inhibitoy effect of excess iodide on the release of T3 from the thyroid.
口服胆囊造影剂可使正常受试者血清T3降低，血清T4和反T3浓度升高。然而，它们对人体促甲状腺激素（TSH）分泌的影响尚不清楚。在本研究中，6名甲状腺功能正常的志愿者中有5名在服用3克碘番酸（IA）5天后，血清TSH浓度高于基线值（升高具有临界显著性），且IA给药后TSH对促甲状腺激素释放激素（TRH）的反应显著增强。在另外4名3天前已接受IA的甲状腺功能正常的受试者中，接下来2天给予T3（5微克，每日5次）使血清T3浓度恢复至基线值，并阻止了IA诱导的TRH刺激的血清TSH浓度升高。从本研究得出的结论是，IA增强了垂体促甲状腺细胞对TRH的敏感性，并且这种作用可能至少部分与IA诱导的循环T3降低以及先前证明的IA对垂体将T4转化为T3的抑制作用有关。IA给药后血清T3浓度降低主要是由于抑制了T4的外周5-单脱碘作用，并且可能是由于过量碘对甲状腺释放T3的直接抑制作用。
