Abstract：
BACKGROUND: The thyrotropin-releasing hormone (TRH) stimulation test is used to diagnose pituitary pars intermedia dysfunction (PPID) using 10- or 30-min protocols. Imprecise sampling time for the 10-min protocol can lead to misdiagnoses.
OBJECTIVE: To determine the effect of imprecise sampling time for the 30-min protocol of the TRH stimulation test.
METHODS: In vivo experiment.
METHODS: Plasma immunoreactive adrenocorticotropin (ACTH) concentrations were measured 9, 10, 11, 29, 30 and 31 min after intravenous administration of 1 mg of TRH in 15 control and 12 PPID horses. Differences in ACTH concentrations between sampling times, variability in ACTH concentrations between protocols, and diagnostic classification of PPID were assessed using Friedman\'s test, Bland-Altman plots, and Fisher\'s exact test, respectively, with 95% confidence intervals reported and significance set at p < 0.05.
RESULTS: Imprecise sampling time resulted in variable ACTH concentrations, but significant differences in absolute ACTH concentrations were not detected for imprecise sampling within each protocol or between protocols. Imprecise sampling changed PPID diagnostic classification for 3/27 (11 [4-28] %) horses for both protocols. Using the 30-min protocol as a reference, 1/12 (8 [1-35] %) horses returned a negative test result and 5/12 (42 [19-68] %) horses returned equivocal test results that would be considered positive in practice due to the presence of supportive clinical signs.
CONCLUSIONS: Limited sample size and inter-horse variability reduced the ability to detect small but potentially relevant differences.
CONCLUSIONS: Overall, the impact of imprecise sampling was not significantly different between the 10- and 30-min TRH stimulation test protocols. However, diagnostic classification for PPID would have varied between the 10- and 30-min protocols in this population, if clinical signs had been ignored. Precise timing during TRH stimulation tests and contextual interpretation of ACTH concentrations remain fundamental for the diagnosis of PPID.
OBJECTIVE: To determine the effect of imprecise sampling time for the 30-min protocol of the TRH stimulation test.
METHODS: In vivo experiment.
METHODS: Plasma immunoreactive adrenocorticotropin (ACTH) concentrations were measured 9, 10, 11, 29, 30 and 31 min after intravenous administration of 1 mg of TRH in 15 control and 12 PPID horses. Differences in ACTH concentrations between sampling times, variability in ACTH concentrations between protocols, and diagnostic classification of PPID were assessed using Friedman\'s test, Bland-Altman plots, and Fisher\'s exact test, respectively, with 95% confidence intervals reported and significance set at p < 0.05.
RESULTS: Imprecise sampling time resulted in variable ACTH concentrations, but significant differences in absolute ACTH concentrations were not detected for imprecise sampling within each protocol or between protocols. Imprecise sampling changed PPID diagnostic classification for 3/27 (11 [4-28] %) horses for both protocols. Using the 30-min protocol as a reference, 1/12 (8 [1-35] %) horses returned a negative test result and 5/12 (42 [19-68] %) horses returned equivocal test results that would be considered positive in practice due to the presence of supportive clinical signs.
CONCLUSIONS: Limited sample size and inter-horse variability reduced the ability to detect small but potentially relevant differences.
CONCLUSIONS: Overall, the impact of imprecise sampling was not significantly different between the 10- and 30-min TRH stimulation test protocols. However, diagnostic classification for PPID would have varied between the 10- and 30-min protocols in this population, if clinical signs had been ignored. Precise timing during TRH stimulation tests and contextual interpretation of ACTH concentrations remain fundamental for the diagnosis of PPID.
摘要：
背景：促甲状腺激素释放激素（TRH）刺激试验用于使用10分钟或30分钟方案诊断垂体中层间功能障碍（PPID）。10分钟方案的不精确采样时间可能导致误诊。
目的：确定不精确的采样时间对TRH刺激试验30分钟方案的影响。
方法：体内实验。
方法：在15匹对照和12匹PPID马静脉注射1mgTRH后9、10、11、29、30和31分钟，测量血浆免疫反应性促肾上腺皮质激素（ACTH）浓度。采样时间之间ACTH浓度的差异，协议之间ACTH浓度的可变性，PPID的诊断分类使用弗里德曼试验进行评估，Bland-Altman阴谋,和费希尔的精确检验，分别,报告95%置信区间，显著性设置为p<0.05。
结果：采样时间不精确导致ACTH浓度变化，但在每个方案或方案之间的不精确采样中未检测到绝对ACTH浓度的显著差异.两种方案的不精确采样改变了3/27（11[4-28]％）马的PPID诊断分类。使用30分钟协议作为参考，1/12（8[1-35]％）马匹返回阴性测试结果，5/12（42[19-68]％）马匹返回模棱两可的测试结果，由于存在支持性临床症状，在实践中被认为是阳性的。
结论：有限的样本量和马间变异性降低了检测微小但潜在相关差异的能力。
结论：总体而言，不精确采样的影响在10分钟和30分钟TRH刺激试验方案之间没有显著差异.然而,在该人群中，PPID的诊断分类在10分钟和30分钟协议之间会有所不同，如果临床症状被忽视。TRH刺激测试期间的精确时机和ACTH浓度的上下文解释仍然是诊断PPID的基础。
目的：确定不精确的采样时间对TRH刺激试验30分钟方案的影响。
方法：体内实验。
方法：在15匹对照和12匹PPID马静脉注射1mgTRH后9、10、11、29、30和31分钟，测量血浆免疫反应性促肾上腺皮质激素（ACTH）浓度。采样时间之间ACTH浓度的差异，协议之间ACTH浓度的可变性，PPID的诊断分类使用弗里德曼试验进行评估，Bland-Altman阴谋,和费希尔的精确检验，分别,报告95%置信区间，显著性设置为p<0.05。
结果：采样时间不精确导致ACTH浓度变化，但在每个方案或方案之间的不精确采样中未检测到绝对ACTH浓度的显著差异.两种方案的不精确采样改变了3/27（11[4-28]％）马的PPID诊断分类。使用30分钟协议作为参考，1/12（8[1-35]％）马匹返回阴性测试结果，5/12（42[19-68]％）马匹返回模棱两可的测试结果，由于存在支持性临床症状，在实践中被认为是阳性的。
结论：有限的样本量和马间变异性降低了检测微小但潜在相关差异的能力。
结论：总体而言，不精确采样的影响在10分钟和30分钟TRH刺激试验方案之间没有显著差异.然而,在该人群中，PPID的诊断分类在10分钟和30分钟协议之间会有所不同，如果临床症状被忽视。TRH刺激测试期间的精确时机和ACTH浓度的上下文解释仍然是诊断PPID的基础。
