Eiler H, Oliver J W, Andrews F M, Fecteau K A, Green E M, McCracken M
Department of Animal Science, College of Veterinary Medicine, University of Tennessee, Knoxville 37996-4500, USA.
J Am Vet Med Assoc. 1997 Jul 1;211(1):79-81.
To evaluate results of a combined dexamethasone suppression/thyrotropin-releasing hormone (TRH) stimulation test in horses suspected clinically to have a pars intermedia pituitary adenoma (PIPA).
Case-control study.
7 healthy adult horses and 5 horses suspected to have a PIPA.
A baseline blood sample was collected, and dexamethasone (40 micrograms/kg [18 micrograms/lb] of body weight, IV) was administered; a second blood sample was collected 3 hours later, and TRH (1.1 mg, IV) was administered; serial blood samples were collected 15, 30, 45, 60, and 90 minutes and 21 hours after TRH administration (24 hours after dexamethasone injection). Cortisol concentration was determined for all blood samples.
Baseline cortisol concentration was significantly lower in horses suspected to have a PIPA than in healthy horses. Cortisol concentration was suppressed by dexamethasone in both groups; however, after TRH administration, cortisol concentration returned to baseline values in horses suspected to have a PIPA, but not in healthy horses. Concentration was still less than the baseline value 24 hours after dexamethasone administration in healthy horses.
The combined dexamethasone suppression/TRH stimulation test may be a useful diagnostic test in horses suspected to have a PIPA. For clinical application, collection of a blood sample 30 minutes after TRH administration is recommended.
评估对临床疑似垂体中间部腺瘤（PIPA）的马匹进行地塞米松抑制/促甲状腺激素释放激素（TRH）刺激联合试验的结果。
病例对照研究。
7匹健康成年马和5匹疑似患有PIPA的马。
采集一份基础血样，静脉注射地塞米松（40微克/千克[18微克/磅]体重）；3小时后采集第二份血样，然后静脉注射TRH（1.1毫克）；在注射TRH后15、30、45、60和90分钟以及21小时（地塞米松注射后24小时）采集系列血样。测定所有血样中的皮质醇浓度。
疑似患有PIPA的马匹的基础皮质醇浓度显著低于健康马匹。两组马匹的皮质醇浓度均被地塞米松抑制；然而，注射TRH后，疑似患有PIPA的马匹的皮质醇浓度恢复到基础值，而健康马匹则未恢复。健康马匹在注射地塞米松24小时后浓度仍低于基础值。
地塞米松抑制/TRH刺激联合试验可能是疑似患有PIPA的马匹的一种有用的诊断试验。对于临床应用，建议在注射TRH后30分钟采集血样。
